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diff --git a/38036-h/38036-h.htm b/38036-h/38036-h.htm new file mode 100644 index 0000000..ce628c4 --- /dev/null +++ b/38036-h/38036-h.htm @@ -0,0 +1,5637 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /> +<title>The Project Gutenberg eBook of Electricity for the 4-H Scientist, by Eric B. Wilson</title> + <style type="text/css"> + + blockquote { + text-align:justify; + } + + body { + margin-left:10%; + margin-right:10%; + } + + .booktitle { + letter-spacing:3px; + } + + .center { + text-align:center; + font-weight:bold; + } + + div.center { + text-align:center; + } + + div.center table { + margin-left:auto; + margin-right:auto; + text-align:left; + } + + div.inset12, div.inset20, div.inset26 { + margin-top:1em; + margin-bottom:1em; + margin-left:auto; + margin-right:auto; + } + + div.inset12 { + width:12em + } + + div.inset20 { + width:20em + } + + div.inset26 { + width:26em + } + + div.inset12 p, div.inset20 p, div.inset26 p { + text-indent:0; + } + + .figcenter { + padding:1em; + text-align:center; + font-size:0.8em; + border:none; + margin:auto; + text-indent:1em; + } + + .h1 { + font-size:2em; + margin:.67em 0; + } + + .h1, .h2, .h3, .h4, .h5, .h6 { + font-weight:bolder; + text-align:center; + text-indent:0; + } + + h1, h2, h3, h4, h5, h6 { + text-align:center; + } + + .h2 { + font-size:1.5em; + margin:.75em 0; + } + + .h3 { + font-size:1.17em; + margin:.83em 0; + } + + .h4 { + margin:1.12em 0 ; + } + + .h5 { + font-size:.83em; + margin:1.5em 0 ; + } + + h5 { + margin-bottom:1%; + margin-top:1%; + } + + .h6 { + font-size:.75em; + margin:1.67em 0; + } + + hr.chapter { + margin-top:6em; + margin-bottom:4em; + } + + p { + text-align:justify; + margin-top:.75em; + margin-bottom:.75em; + text-indent:0; + } + + p.caption { + text-indent:0; + text-align:center; + margin-bottom:2em; + } + + p.hang { + margin-left:2em; + text-indent:-2em; + } + + p.margin20 { + margin-right:20px; + margin-left:20px; + } + + p.right { + text-align:right; + } + + p.spacer { + margin-top:2em; + margin-bottom:3em; + } + + .pagenum { +/* visibility:hidden; remove comment out to hide page numbers */ + position:absolute; + right:2%; + font-size:75%; + color:gray; + background-color:inherit; + text-align:right; + text-indent:0; + font-style:normal; + font-weight:normal; + font-variant:normal; + } + + .split { + float: left; + clear: left; + padding-right: 2%; + padding-left: 0; + padding-top: 0; + padding-bottom: 0; + } + + .splitr { + float: right; + clear: right; + padding-right: 0; + padding-left: 2%; + padding-top: 0; + padding-bottom: 0; + } + + .tdc { + text-align:center; + } + + .tdl { + text-align:left; + } + + .tdli { + font-style: italic; + text-align:left; + } + + .tdr { + text-align:right; + padding-right:1em; + } + + .topbox { + color:black; + border:2px solid black; + } + + .topbox400 { + width:400px; + color:black; + border:2px solid black; + } + + hr.full { width: 100%; + margin-top: 3em; + margin-bottom: 0em; + margin-left: auto; + margin-right: auto; + height: 4px; + border-width: 4px 0 0 0; /* remove all borders except the top one */ + border-style: solid; + border-color: #000000; + clear: both; } + pre.pg {font-size: 85%;} + </style> +</head> +<body> +<h1>The Project Gutenberg eBook, Electricity for the 4-H Scientist, by Eric B. +Wilson</h1> +<pre class="pg"> +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at <a href = "http://www.gutenberg.org">www.gutenberg.org</a></pre> +<p>Title: Electricity for the 4-H Scientist</p> +<p> Idaho Agricultural Extension Service Bulletin 396, June, 1962</p> +<p>Author: Eric B. Wilson</p> +<p>Release Date: November 16, 2011 [eBook #38036]</p> +<p>Language: English</p> +<p>Character set encoding: ISO-8859-1</p> +<p>***START OF THE PROJECT GUTENBERG EBOOK ELECTRICITY FOR THE 4-H SCIENTIST***</p> +<p> </p> +<h3>E-text prepared by<br /> + Kevin Handy, John Hagerson, Matthew Wheaton,<br /> + and the Online Distributed Proofreading Team<br /> + (http://www.pgdp.net)</h3> +<p> </p> +<hr class="full" /> +<p> </p> +<p> </p> + +<div class="figcenter topbox400"> +<img src="images/cover.jpg" width="400" height="510" alt="" /> +</div> + +<p class="spacer"> </p> + +<p class="h6">IDAHO Agricultural<br /> +Extension Service</p> + +<p class="spacer"> </p> + +<p class="h6">BULLETIN 396<br /> +JUNE, 1962<br /> +T-1</p> + +<p class="spacer"> </p> + +<h1 class="booktitle">ELECTRICITY for the 4-H scientist</h1> + +<p class="spacer"> </p> + +<p class="h3">Safety<br /> +Uses<br /> +Economy</p> + +<p class="spacer"> </p> + +<p class="h6">DIVISION I<br /> +4-H ELECTRIC</p> + +<p class="spacer"> </p> + +<p class="h4">UNIVERSITY OF IDAHO<br /> +<i>College of Agriculture</i></p> + +<hr class="chapter" /> + +<h2 id="How_to">HOW TO USE THIS BOOK IN FULFILLING THE GOALS OF THE 4-H ELECTRIC PROJECT +FOR THE FIRST AND SUCCEEDING YEARS</h2> + +<p>The minimum goals for credit in the +4-H Electric project vary according to the +4-H member's age and the number of years +he or she has taken the electric project. For +example, if you are a 4-H member beginning +the 4-H Electric project at the age of 10, +you will not be required to earn as many +credit points as a 14-year-old 4-H member +beginning the 4-H Electric project. However, +if you are a 12-year-old in your second +year of electricity you must earn as +many credit points in that year as a 14-year-old +does in his or her first year.</p> + +<p>Each lesson or goal has been designated +a certain number of credit points. These +are shown near the title of each lesson or +goal. You decide on the lessons you want +to study, list them, and add up the credit +points.</p> + +<p>For a full year's 4-H project credit, the +total of your credit points should be at least +as many as shown in the following table:</p> + +<p>Examples of reading the table below are +as follows: (a) An 11-year-old member is +required to complete 13 credit points the +first year, (b) A 14-year-old is required to +complete 17 credit points his first year, (c) +A 14-year-old taking the electric project for +the third year must complete 16 credit points +that year.</p> + +<p>We recommend that, if you are taking +the 4-H Electric project, you start with the +first lesson in the book and go on through +to the back of the book in advanced years. +But you may skip the less important or less +interesting parts so long as you learn the +basic lessons. A way to find out whether +you know the basic lessons is to read them +through and try to answer all questions +under the heading "What Did You Learn." +If you can answer these questions you may +not wish to spend the time doing the things +listed under "What To Do."</p> + +<p>Minimum Number of Credit Points +Required for Each Year's Work in the 4-H Electric Project</p> + +<p class="spacer"></p> + +<div class="center"> +<table border="2" cellpadding="4" cellspacing="0" summary="Year's Work"> + <tr> + <td class="tdl">4-H Member's Age</td> + <td class="tdc" colspan="4">4-H Member's Year in 4-H Electric Project</td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdc">1st Year</td> + <td class="tdc">2nd Year</td> + <td class="tdc">3rd Year</td> + <td class="tdc">4th or<br /> Later Years</td> + </tr> + <tr> + <td class="tdl">10-11</td> + <td class="tdc">13</td> + <td class="tdc">15</td> + <td class="tdc"> </td> + <td class="tdc"> </td> + </tr> + <tr> + <td class="tdl">12-13</td> + <td class="tdc">15</td> + <td class="tdc">17</td> + <td class="tdc">19</td> + <td class="tdc">20</td> + </tr> + <tr> + <td class="tdl">14-15</td> + <td class="tdc">17</td> + <td class="tdc">19</td> + <td class="tdc">21</td> + <td class="tdc">21</td> + </tr> + <tr> + <td class="tdl">16 & over</td> + <td class="tdc">19</td> + <td class="tdc">21</td> + <td class="tdc">21</td> + <td class="tdc">21</td> + </tr> +</table></div> + +<p><br />This system of credit points makes it possible for you to do the things you want to do with +electricity and get credit for them in the 4-H Electric project.</p> + +<p class="spacer"> </p> + +<p class="h4">4-H Electric, Division I</p> + +<p class="spacer"> </p> + +<hr class="chapter" /> + +<h2>TABLE OF CONTENTS</h2> + +<div class="center"> +<table border="0" cellpadding="4" cellspacing="20" summary="Table of Contents"> + <tr> + <td class="tdr">Lesson<br />Number</td> + <td class="tdc">Title</td> + <td class="tdc">Credit<br />Points</td> + <td class="tdc">Page<br />Number</td> + </tr> + <tr> + <td class="tdr"> </td> + <td class="tdl"><a href="#How_to">How to Use This Book</a></td> + <td> </td> + <td class="tdc">1</td> + </tr> + <tr> + + <td class="tdr"><a href="#LESSON_NO_B-l">B-1</a></td> + <td class="tdl">Getting Acquainted With Electricity</td> + <td class="tdc">3</td> + <td class="tdc">2</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-2">B-2</a></td> + <td class="tdl">Tools for Electricians</td> + <td class="tdc">4</td> + <td class="tdc">7</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-3">B-3</a></td> + <td class="tdl">Rewire a Lamp—Be a Lamp Detective</td> + <td class="tdc">3</td> + <td class="tdc">11</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-4">B-4</a></td> + <td class="tdl">Make a Trouble Light</td> + <td class="tdc">3</td> + <td class="tdc">15</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-5">B-5</a></td> + <td class="tdl">What Makes Motors Run</td> + <td class="tdc">5</td> + <td class="tdc">18</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-6">B-6</a></td> + <td class="tdl">Taking Care of Electric Motors</td> + <td class="tdc">3</td> + <td class="tdc">23</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-7">B-7</a></td> + <td class="tdl">Reading the Electric Meter</td> + <td class="tdc">4</td> + <td class="tdc">26</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-8">B-8</a></td> + <td class="tdl">Ironing is Fun</td> + <td class="tdc">3</td> + <td class="tdc">30</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-9">B-9</a></td> + <td class="tdl">Let's Be Friends With Electricity</td> + <td class="tdc">2</td> + <td class="tdc">35</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-10">B-10</a></td> + <td class="tdl">How Electric Bells Work—For You</td> + <td class="tdc">3</td> + <td class="tdc">39</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-11">B-11</a></td> + <td class="tdl">First Aid for Electrical Injuries</td> + <td class="tdc">2</td> + <td class="tdc">43</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-12">B-12</a></td> + <td class="tdl">How Electricity Heats</td> + <td class="tdc">3</td> + <td class="tdc">47</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-13">B-13</a></td> + <td class="tdl">Mysterious Magnetism</td> + <td class="tdc">2</td> + <td class="tdc">50</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-14">B-14</a></td> + <td class="tdl">Give Your Appliances and Lights a Square Meal</td> + <td class="tdc">2</td> + <td class="tdc">54</td> + </tr> + <tr> + <td class="tdr"><a href="#LESSON_NO_B-15">B-15</a></td> + <td class="tdl">You Can Measure Electricity</td> + <td class="tdc">4</td> + <td class="tdc">58</td> + </tr> +</table></div> + +<p class="spacer"> </p> + +<p class="h5">UNIVERSITY OF IDAHO<br /> +COLLEGE OF AGRICULTURE<br /> +AGRICULTURAL EXTENSION SERVICE<br /> +Eric B. Wilson, Extension Agricultural Engineer<br /> +1962</p> + +<p>Published and distributed in furtherance of the Acts of May 8 and June 30, 1914, by the +University of Idaho Extension Service, James E. Kraus, Director; and the U. S. Department +of Agriculture, Co-operating.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[2]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-l">LESSON NO. B-1</h2> + +<p class="h4">Credit Points 3</p> + +<p class="h3">GETTING ACQUAINTED WITH ELECTRICITY</p> + +<p>Electricity serves you best when you understand +how it works and use it properly. +As a 4-H member, you should know about +electricity and help to show others the way to +obtain its tremendous work-saving benefits as +well as how to use it with safety.</p> + +<p>A good way to think of electricity is to +compare it with water. It acts a lot like water. +However it is made of tiny parts of atoms +called electrons. When there are more than +the normal number of electrons in anything, +it is said to be negatively charged; when there +is a shortage of electrons, it is positively +charged. As water flows downhill, "seeking +it's level," electrons flow from negative to +positive, seeking to "balance" the charge.</p> + +<h3>Electrical Conductors</h3> + +<p>Even if you're never going to repair a +lamp or make a chick brooder, you should +know about conductors and insulators. This +is because you happen to be a fairly good +conductor of electricity. Electricity will pass +easily through you to other conductors—the +ground, for instance. When this happens you +may get a shock, burn, or serious injury. +But it doesn't ever have to happen, if you learn +to understand your friend, electricity.</p> + +<p>Silver, copper, iron, aluminum and many +other metals are very good conductors. +Water, acids, and salts are too. Electricity +passes over or through them very easily. +Like water pipes, the larger the conductor, +the more electricity it can carry. When conductors +are too small for the amount of +electrons trying to move over them, they get +hot, melt, may start fires. That's why wire +size is important.</p> + +<h3>Electrical Insulators</h3> + +<p>Insulators are the opposite of conductors. +Electricity has trouble passing through some +materials. Rubber, most plastics, dry wood, +oils and glass are some of the good insulators. +It's the amount and kind of insulation +that counts. If it has enough force, electricity +can pass through just about anything—even +jump gaps!</p> + +<p>Electricity, like water, flows along the +easiest paths. It is always trying to get to +the ground. The earth attracts it. It stays +on the wires unless a person, a wet branch, +or some other conductor gives it a path to +the ground. Do not touch any wire which +might be carrying electricity.</p> + +<div class="figcenter"> +<img src="images/p02_blackboard.jpg" width="300" height="275" alt="" /> +</div> + +<h3>Play It Safe</h3> + +<p>If you should touch a "hot" wire accidentally +and are standing on a dry piece of +wood, the conducting pathway to the ground is +not good and the electricity may keep running +along its wire. But do not touch some +other conductor with another part of your +body. This would complete a circuit through +your body and would be very dangerous. Always +make sure there is plenty of good insulation +material or plenty of distance between +you and anything which might be carrying +electricity.</p> + +<p>Remember, too, insulation is of little use +when it is wet. Dew, mist, rain, condensation, +a damp floor can change the whole picture. +If you understand electricity and how it +acts, you'll be safe enough, because you won't +take chances or expose yourself to injury.</p> + +<p><span class="pagenum">[3]</span></p> + +<h3>Electrical Terms</h3> + +<p><i>Alternating Current</i>—Usually referred to as +"AC," alternating current is current which +reverses its direction of flow at regular +intervals, 60 times a second.</p> + +<p><i>Direct Current</i>—"DC" current flows only in +one direction. Battery current is DC.</p> + +<p><i>Ampere</i>—Amperes are units by which the rate +of flow of electrical current (electrons) is +measured. An ampere is 6.3 billion electrons +passing one point in a circuit, in one second. +This compares with the way the flow of water +is measured in gallons per second.</p> + +<p><i>Volts</i>—A volt is a unit to measure the tendency +of electrons to move when they are +shoved. Voltage is the amount of "push" +behind the electrons. It's like water pressure +in a pipe. Home power lines carry 115 +volts (110 to 120 volts). For appliances +such as electric stoves, washers and driers, +a second 115-volt line should be added, giving +230 volts (220 to 240 volts).</p> + +<p><i>Watts</i>—Watts equal volts times amperes. +Light bulbs, electric irons and other appliances +are usually marked with the voltage +they require and the number of watts.</p> + +<p><i>Kilowatts</i>—Your electric bill usually reads +in kilowatt hours. A kilowatt is 1000 watts. +A kilowatt hour equals 1000 watts used for 1 +hour. One kilowatt equals about 1-1/3 horsepower. +A kilowatt is usually indicated by +"kw" and a kilowatt hour by "kwh."</p> + +<p><i>Circuits</i>—A closed circuit is one in which +the electricity is flowing, lighting a light, running +a motor, or some other appliance. The +circuit runs all the way from the place the +electricity is being generated to your home, +through the appliance or light bulb, and back +to the generator.</p> + +<p>Circuits are opened and closed by +switches. When the circuit is opened, the +electricity stops at the switch. Before working +on a switch, socket, fuse, or any part of +the wiring be sure to open the main switch. +The main switch is usually at the fuse box +or near it. Appliances should be disconnected +when you work on them. Everyone in the +family should know where the main switch is +so it can be pulled in case of accidents, fire, +flood, or windstorm damage.</p> + +<p><i>Fuses and Circuit Breakers</i>—These are the +safety valves of your electrical system. +The different electrical circuits in your home +are meant to carry only certain amounts of +electricity. Some carry only 15 amps, others +can carry 20 or more. They are marked to +show capacity.</p> + +<p>When a fuse burns out or a circuit breaker +opens, look for an overload of lights and +appliances on the circuit before you try to replace +the fuse or close the circuit breaker. +Without these safeguards, the overloaded +electric line will heat up and may start a fire. +Even if no fire starts, electricity will be +wasted and the homeowner will be paying for +electricity that's doing no good.</p> + +<p>Remember: If you ever have to replace +a fuse, pull the main switch first. Keep a +flashlight handy in your house. It seems that +fuses usually blow at night, and it doesn't pay +to stumble or fumble around electric wires +in the dark.</p> + +<div class="figcenter"> +<img src="images/p03_wateranalogy.jpg" width="400" height="230" alt="" /> +</div> + +<p class="spacer"> </p> + +<p><span class="pagenum">[4]</span></p> + +<h3>WHAT TO DO: Make A Circuit Board</h3> + +<p>So that you can show others how electricity +travels from here to there, and how it behaves +under different conditions, make an electric +circuit board.</p> + +<p class="hang"> +<b><i>Materials Needed:</i></b><br /> + Piece of 3/4" board about 4" x 6"<br /> + l-l/2-volt No. 6 dry cell battery<br /> + Two pieces of bell wire, each 24" long, one black, one white<br /> + Two 10-penny box nails (3")<br /> + Three 3-penny box nails (1")<br /> + Two small screws or carpet tacks<br /> + Two 2-inch rubber bands<br /> + Two miniature sockets with solder terminals<br /> + Two l-l/2-volt flashlight bulbs +</p> + +<p class="hang"> +<b><i>Tools Needed:</i></b><br /> + Ruler, pencils, hammer, pliers or vise. +</p> + +<p><b><i>Making the Board:</i></b></p> + +<p class="hang">1. Lay out the board with a pencil and ruler +as indicated in Figure 1.</p> + +<p class="hang">2. Bend the three-inch nail as shown in Figure +2, using pliers, vise and hammer.</p> + +<p class="hang">3. Pound the one-inch nails into the board for +a half-inch at points A, C, and D. Use the +three-inch nail to make a hole a half-inch +deep at B. Put the crank nail in this +hole and pound in a little farther. Attach +the lamp socket brackets at E and F. +Stretch the rubber band as in Figure 3.</p> + +<p class="hang">4. Lay out the electricity path, the circuit +(Figure 3). Use the black wire for the +positive side of the circuit (the center +pole of battery). Twist it around the +switch crank B, and the center pole of +battery. Run another piece to the outside +terminal of bulb socket at E. Run white +piece to negative pole of battery from the +other terminal at E.</p> + +<div class="figcenter"> +<img src="images/p04_fig1.jpg" width="232" height="175" alt="" /> +</div> + +<p class="caption">Figure 1 (Circuit Board)</p> + +<div class="figcenter"> +<img src="images/p04_fig2.jpg" width="222" height="93" alt="" /> +</div> + +<p class="caption">Figure 2 (Switch)</p> + +<p class="hang">5. Close the switch. The rubber band should +hold the switch nail tightly against nail at +C. Does the bulb light? __________ +If it doesn't, check the connections.</p> + +<p>Now you have a circuit—a closed circuit +when the electricity runs all the way from the +positive pole to the negative pole. The black +wire is the hot side, the live wire, because it +carries the full load of the battery up to the +bulb.</p> + +<p>Remember, battery current is direct current, +DC. In the case of alternating current, +AC, such as most homes and buildings use, +the electricity flows in first one direction and +then the other.</p> + +<div class="figcenter"> +<img src="images/p04_fig3.jpg" width="237" height="187" alt="" /> +</div> + +<p class="caption">Figure 3 (Closed Circuit)</p> + +<h3>Parallel Wiring</h3> + +<p>To make this circuit hookup, attach another +white wire to the negative pole of battery +and a terminal of the second flashlight +bulb. Run a black wire from the other terminal +to the switch terminal at C (Figure 4). +Close switch. Both bulbs will light.</p> + +<p>Trace the circuit. Electricity is going +equally to each bulb, the same amount that +went to the single bulb. The difference is that +the battery will last only half as long. It's like +a pail of water with two open spigots. The +pail empties twice as fast as it would with just +one spigot open. This type of wiring is called +parallel wiring. If one bulb is unscrewed, +the other will stay lit.</p> + +<p><span class="pagenum">[5]</span></p> + +<div class="figcenter"> +<img src="images/p05_fig4.jpg" width="237" height="185" alt="" /> +</div> + +<p class="caption">Figure 4 (Parallel Wiring)</p> + +<h3>Series Wiring</h3> + +<p>To do this, run the negative wire to one +terminal of the second bulb and attach a wire +from the other terminal to a terminal of the +first bulb. The other terminal connects with +the switch at C (Figure 5). This is series +wiring. If one bulb is unscrewed, the other +will fail to light because the circuit is broken +for both. Anything that breaks the circuit has +the effect of opening the switch.</p> + +<div class="figcenter"> +<img src="images/p05_fig5.jpg" width="237" height="180" alt="" /> +</div> + +<p class="caption">Figure 5 (Series Wiring)</p> + +<p>Show there is a circuit through the bulb +by screwing and unscrewing it. Also, "jump" +the socket by running the wire from C to the +other terminal of the bulb at E while it is unscrewed. +Bulb at F will light. Trace this +circuit.</p> + +<p class="spacer"> </p> + +<h3>SUGGESTED DEMONSTRATIONS</h3> + +<p>Using the Circuit Board, you can give +many demonstrations of the way electricity +flows, works and behaves.</p> + +<h3>Water And Electricity</h3> + +<p>To help others understand electricity +better, draw a water system on an electric +circuit board paralleling the circuit. For the +battery show a water tank, pipes instead of +wires, faucets instead of switches. Somewhere +on the board paste a comparison of +electrical terms with terms used in describing +water, such as the following:</p> + +<p class="hang"> <br /> +Wire equals Pipe<br /> +Volts equal Pressure<br /> +Amperes equal Rate of Flow - gallons per second<br /> +Watts equal Pressure times Rate of Flow<br /> +Switch equals Faucet<br /> +Current equals Flowing Water +</p> + +<p>Show how to figure the wattage that a circuit +protected by a 15 ampere fuse can handle. +Do it with actual things or cut-out pictures +of light bulbs, irons, toasters, coffee-makers, +etc.</p> + +<p>You know that Amperes times Volts equal +Watts. If the voltage is 115, a 15 amp circuit +can handle 115 volts times 15 amps, or 1725 +watts.</p> + +<p>The name plates on electric motors indicate +the amperage at full load. You can convert +this to watts, of course, by multiplying +amperage by the line voltage. Motors require +an additional amount of electricity when they +start. You need to allow for this fact, so fuses +will not blow or circuits trip when a motor is +turned on. You will learn more about this +when you study electric motors.</p> + +<p class="spacer"> </p> + +<h3>For More Information</h3> + +<p>Your leader has many other sources of +information about electricity and demonstrations +you can perform. Ask him. Also, +libraries have many books about electricity +and its history, which are very interesting and +useful. Maybe you can find an electrician, +someone from your power supplier, or an +equipment dealer who will talk to your club on +electricity or electrical safety.</p> + +<p class="spacer"> </p> + +<p><span class="pagenum">[6]</span></p> + +<h3>What Did You Learn?</h3> + +<p>(Underline the correct answers then discuss in +the group.)</p> + +<p>1. In a water pipe system water flows. In an +electrical circuit (electrons) (atoms) (charges) +flow.</p> + +<p>2. Electricity or electrons flow (easier) (harder) +(about the same) in a conductor than in an +insulator.</p> + +<p>3. Rubber is a good (conductor) (insulator) +(ground).</p> + +<p>4. The most common material used as an electrical +conductor is (glass) (silver) (copper).</p> + +<p>5. The unit of electrical pressure or push is +the (ampere) (volt) (watt).</p> + +<p>6. The rate of flow of electricity is measured +in (gallons) (amperes per minute) (amperes).</p> + +<p>7. Volts times amperes equals (watts) (kilowatt +hours) (alternating current).</p> + +<p>8. A dry cell battery (stores) (makes) (uses) +electrical energy.</p> + +<p>9. In a parallel circuit the electricity has (one) +(two or more) (no) paths to travel.</p> + +<p>10. In a series circuit with two bulbs and a +switch the bulbs are (brighter) (dimmer) (the +same) as when they were in the parallel circuit.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[7]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> +<h2 id="LESSON_NO_B-2">LESSON NO. B-2</h2> + +<p class="h4">Credit Points 4</p> + +<h3><b>TOOLS FOR ELECTRICIANS</b></h3> + +<div class="inset12"> +<p>Who goeth a borrowing<br /> +Goeth a sorrowing<br /> +Few lend (but fools)<br /> +Their working tools</p> +<p class="right">Tusser 1524-1580</p> +</div> + +<p>Whenever a job comes up, it saves time +and trouble when you have the right tools +and they are all where you can find them. +Electrical work takes some special tools +and some everyday tools.</p> + +<p>If you have ever watched a good electrician +at work, you've seen how neatly he +stores his tools in a box so every one +of them is handy. When a lineman climbs a +pole, he has his regular tools in a holster on +his belt. Special tools are kept in a box in +racks in the repair truck, all ready for instant +use. Wouldn't you like to have electrician's +tools all handy, ready for use, and +know how to use them properly?</p> + +<h3>Basic Tools for Electrical Work</h3> + +<div class="figcenter"> +<img src="images/p07_tools.jpg" width="350" height="103" alt="" /> +</div> + +<p><i>Knife</i></p> + +<p>A good knife with a sharp blade is one of +the most useful tools. A camper's or electrician's +type knife is probably best because +it has other useful parts besides the cutting +blades—a screwdriver or punch, for instance. +Of course, you'll never use the cutting blades +as a screwdriver. This knife should be kept clean, +dry, sharp, and free from rust. Put +a little oil on the joints from time to time. +Remember, "Never whittle toward you and +you'll never cut yourself."</p> + +<p><i>Pliers</i></p> + +<p>A pair of electrician's pliers should be +part of your kit. Wrap the handles with +plastic insulating tape. Even though you're +not going to work on "hot" electric lines, +it pays to play safe. Later on, as you learn more +about electricity, you'll want a pair of +needle-nose pliers for the fine work.</p> + +<p><i>Screwdrivers</i></p> + +<p>You'll want a screwdriver which has true +corners. A 4 to 6 inch plastic handled screwdriver +with a narrow blade is best. You'll +probably need more than one size to fit the +various size screws you'll be turning.</p> + +<p><span class="pagenum">[8]</span></p> + +<p>Screwdrivers are easily damaged if you +try to use them as chisels and pry bars, or +use them in screw slots which are too large +for the blade.</p> + +<p>You can be hurt by the screwdriver if +you try to screw or unscrew things you are +holding in your hand. Keep your free hand +away from the end of the screwdriver. Place +the work on a bench or where it can be +handled easily.</p> + +<p><i>Soldering Iron</i></p> + +<p>A good 100 to 250-watt electric soldering +iron will be useful. Later on you may want +to buy a soldering gun, but unless you are doing +a lot of soldering it won't be necessary. +A supply of resin-core electrician's solder +will be needed. Acid-core solder reacts +with copper and in time causes a bad splice.</p> + +<div class="figcenter"> +<img src="images/p07_soldering.jpg" width="287" height="295" alt="" /> +</div> + +<p><i>Tape</i></p> + +<p>Once it was necessary to use two types of +tape on splices—rubber tape with friction +tape over it. Now there is a plastic tape on +the market which takes the place of both and +has good insulating quality. It is called +electrical tape, or plastic tape, and resists +water, oils (which would damage rubber tape), +and acids. You'll need a lot of tape in your +electrical work, so keep a roll on hand.</p> + +<p><i>Other Tools and Equipment</i></p> + +<p>As you go along in electrical work, you'll +be adding tools and other equipment, such as +a trouble light and maybe an ammeter or +voltmeter. Other tools you'll want to add will +be a Phillips screwdriver, open end wrenches, +a crescent wrench, small hack saw, hand drill +and bits.</p> + +<p>You'll also be using some regular carpenter's +tools such as hammers, saws, and so on. +Unless you use them frequently, you don't +need to keep them in your electrical kit.</p> + +<p>It's a good idea to start acquiring a supply +of electrical parts—lengths of wire, fuses, +switches, sockets, plugs, and other items that +will come in handy. There are parts you can +salvage from old lamps, motors, and other +equipment. Such a collection can be a real +treasure chest when you need a part in a +hurry. But be sure to throw away all faulty +parts.</p> + +<div class="figcenter"> +<img src="images/p08_fig1.jpg" width="212" height="175" alt="" /> +</div> + +<p class="caption">Figure 1. Completed tool chest.</p> + +<p class="spacer"> </p> + +<h3>WHAT TO DO: Build a Tool Chest</h3> + +<p>To keep your tools always ready for use, +a tool chest will be very handy. It's the 4-H +way to work. You'll be surprised how much +easier it makes a job when you have your +tools, various parts and repair equipment all +in one place. You can make the chest (Figure 1) +with a saw, plane, screwdriver, pencil, +ruler or carpenter's square, and hammer.</p> + +<p><i>Materials You'll Need:</i></p> + +<p class="hang">A piece of lumber 1" by 10" by 8 feet +long. (1" lumber is actually only 3/4" thick—this +is the thickness you'll be working with.)<br /> +2 small hinges, with wood screws<br /> +1 small hasp, with wood screws<br /> +2 small handles with wood screws, or one +large handle<br /> +1 small chain, 10" to 12" long<br /> +Some No. 6 penny finishing nails or wood +screws about the same length</p> + +<p><i>Making The Chest:</i></p> + +<p>1. Cut your lumber into the following +pieces:</p> +<p><span class="pagenum">[9]</span></p> +<p>1 piece 10" x 18" for top</p> + +<p>1 piece 8-1/2" x 16-1/2" for bottom</p> + +<p>2 pieces 6" x 8-1/2" for two ends</p> + +<p>2 pieces 6" x 18" for front and back</p> + +<p>2. Lay out pieces as shown in Figure 2.</p> + +<div class="figcenter"> +<img src="images/p09_fig2.jpg" width="212" height="160" alt="" /> +</div> + +<p class="caption">Figure 2.</p> + +<p>Then, set up the two end pieces and nail +to bottom section. Refer back to Figure 1 as +you go along to see that box is shaping up as +shown. Nail the front and back sections to +the ends along the bottom. Wood screws can +be used instead of nails.</p> + +<p>3. Lay the top in place and attach hinges +to the back side, about two inches in from +each end.</p> + +<p>4. Attach one part of hasp to the top, and +the other part to front board in center. Fasten +the handles to each end.</p> + +<p>5. Attach chain to the top and front so the +top will stay open when chain is fully extended.</p> + +<p>Now you can invent your own improvements +for your chest. You can paint it, put +your name on it, and your club emblem and +name if you wish. You can put a rack on the +inside of the cover to hold your work sheets +and other booklets and materials. You can install +special slots or straps to hold each tool +in its place along the sides of the box. Maybe +you will want to put some partitions in the +box to separate various electrical equipment +such as wires, fuses, switches, and plugs.</p> + +<p><i>A Working Kit</i></p> + +<p>An accessory which you may want to add +to your tool chest is an apron or holster to +wear when you are moving around on the job. +An apron can be made of a size of cloth about +18 by 20 inches. It should be folded up from +the bottom, and sewn to fit the number and size +of tools you have. Figure 3 shows such an +apron.</p> + +<div class="figcenter"> +<img src="images/p09_fig3.jpg" width="225" height="155" alt="" /> +</div> + +<p class="caption">Figure 3. Apron</p> + +<p>You can make a lineman's holster in the +same way, using plastic or soft leather. +Merely make belt loops by cutting on the +dotted lines. A snap fastener will hold the +flap over the tools so they won't fall out.</p> + +<div class="figcenter"> +<img src="images/p09_fig4.jpg" width="175" height="163" alt="" /> +</div> + +<p class="caption">Figure 4. Lineman's Holster.</p> + +<p class="spacer"> </p> + +<p><span class="pagenum">[10]</span></p> + +<h3>Demonstrations You Can Give</h3> + +<p>Show and tell others the proper handling, +care and use of tools.</p> + +<p>Show and tell how to build an electrician's +tool kit.</p> + +<p class="spacer"> </p> + +<h3>For Further Information</h3> + +<p>Ask your power supplier or an electrician +to tell the club about the various tools of the +electrician's trade and demonstrate them. +Ask your leader how to get exhibit material +or information about electrical tools and their +use and then tell the club about them.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[11]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-3">LESSON NO. B-3</h2> + +<p class="h4">Credit Points 4</p> + +<p class="h3"><b>REWIRE A LAMP—BE A LAMP DETECTIVE</b></p> + +<div class="figcenter"> +<img src="images/p11_lineup.jpg" width="400" height="133" alt="" /> +</div> + +<p class="caption">The Line-Up Of Lamp Suspects</p> + +<p>One of the duties of a law officer is to +prevent crime. It's that way with the +lamp detective. You can become one. In the +average home there are lamps about to commit +the crime of shocking people, starting +fires, and stealing electricity. Some are refusing +to do their job well and some are no-goods, +sitting in closets or attics, doing +nothing. You can put these lamps to working +again safely and well. Become the lamp expert +in your family.</p> + +<h3>What's In A Lamp?</h3> + +<p>A lamp gives light for comfortable and +convenient use in the home. It consists +normally of a stand, switch, cord, lampshade +holder, and shade. Some lamps have diffusing +bowls which reduce glare and shadows.</p> + +<p>The most common fault found in an old +lamp is in the cord, but sometimes the +switch or the wiring in the lamp is bad. Look +over all the lamps in your home and find +the ones needing to be fixed.</p> + +<h3>WHAT TO DO—Rewire A Lamp</h3> + +<p>Somewhere around your house you can +probably find a lamp that is no longer used or +needs repairing. You can make it useful again +and at the same time learn how to wire a lamp.</p> + +<p><i>Materials Needed</i>:</p> + +<p>Tools: Pocket knife, small or medium +screwdriver, and pliers (electrician type is +best).</p> + +<p><i>New Lamp Cord</i>: For each lamp to be rewired, +you'll need 6 feet of cord plus the +length of wire within the lamp stand. Lamp +cord wire comes in two sizes, No. 18 and No. +16 AWG (American Wire Gauge). No. 18 is +smaller than No. 16, but is adequate for most +lamps. Cords are made with surface coverings +of several different materials: braided +cotton, rayon or silk, and molded rubber or +plastic. Braided cord is decorative, but rubber +or plastic is easier to work with and is +usually more desirable.</p> + +<p><i>Switch</i>: If the switch is bad, get a new one. +Socket switches are made with push-through, +turn-knob, or pull-chain controls. The pull-chain +type is seldom used on modern table or +floor lamps. Your lamp may have a separate +push-switch in the base. In this case, get the +same kind for replacement. Some switches +are "3-circuit" switches for use with high, +medium, and low-light bulbs.</p> + +<p><i>Plug</i>: Plugs are made of various materials, +mostly hard rubber or molded plastic. +Some have a shank or handle for better grasping. +This type is more desirable. The plug +on the old cord may be good, and if so, may +be used on the new cord.</p> + +<h3>How To Do It:</h3> + +<p>1. If the plug on the old cord is good and you +plan to use it, remove it from the old cord.</p> + +<p>2. Measure and cut a new lamp cord equal to +the length of the cord within the lamp, plus +6 feet.</p> + +<p><span class="pagenum">[12]</span></p> + +<p>3. Pass one end of the new cord through the +center of the plug. Strip 2 inches of the +fabric insulation off cord, or in case of a +rubber cord, split cord back two inches. Be +sure no bare wire shows in long split section +(Figure 1).</p> + +<p>4. Use knife to strip insulation off wire for +3/4" on end of each cord. Be careful. Don't +cut yourself. Don't cut wires. Use a light +touch, slope the knifeblade and slice with knife +edge away from you (Figure 1).</p> + +<div class="figcenter"> +<img src="images/p12_fig1.jpg" width="237" height="100" alt="" /> +</div> + +<p class="caption">Figure 1 (Ready to Wire Plug)</p> + +<p>5. Twist exposed strands of each wire tightly +to make a good conductor, and place each +conductor around its proper terminal in the +direction in which the screw tightens (Figure 2).</p> + +<p>6. Tighten screws on terminal posts. Pull +cord until slack is out. Lay aside until ready +to attach to lamp.</p> + +<div class="figcenter"> +<img src="images/p12_fig2.jpg" width="237" height="150" alt="" /> +</div> + +<p class="caption">Figure 2 (Attaching Cord to Plug)</p> + +<p>7. Remove lamp shade, shade-holder, bulb, +and diffusing bowl, if there is one.</p> + +<p>8. Separate the metal shell of socket from its +cap by pressing on shell at place marked +"press," and pull socket from cap.</p> + +<p>9. Pull on socket body to get some slack in +lamp cord. Loosen screws and detach cord. +Pull cord out through base of lamp. You can +splice new cord to the old one and use the +latter to "string" the new wire.</p> + +<p>10. Pass the new cord up through the lamp +base and socket cap, tie a simple half-hitch +knot in the cord to prevent strain on +the terminals, and attach wires to the terminals +on the socket (Figure 3). If there is +likely to be any strain on cord, use an Underwriters' +knot. Twist strands and attach wire +in direction in which screw tightens.</p> + +<p>11. Pull slack out of cord in lamp so that +socket rests in socket cap, replace shell and +reconnect cap. Be sure the fiber insulator +is in the shell. You'll feel or hear a click +when the notches in shell are locked to the +projections in the cap.</p> + +<p>12. Replace bulb, inspect carefully, and test. +(In floor lamps where the cord runs through +the center post and out under the base, the +cord will last longer if it is fastened with +tape so it doesn't rub edge of lamp base +when lamp is moved.)</p> + +<p>13. If the lamp has a porcelain socket, +simply disconnect the wires at the terminals, +remove the old wire and connect the +new one.</p> + +<div class="figcenter"> +<img src="images/p12_fig3.jpg" width="175" height="325" alt="" /> +</div> + +<p class="caption">Figure 3 (Socket and Switch Assembly)</p> + +<p><span class="pagenum">[13]</span></p> + +<h3>What Did You Learn?</h3> + +<p>Underline correct answers then discuss in the +group. (There may be more than one correct +answer.)</p> + +<p>1. The part of the lamp that usually wears +out first is (the socket) (the cord) (the +plug).</p> + +<p>2. Lamps that waste electricity are those +which have (bad wiring) (frayed cords) (dirty +shades or bulb).</p> + +<p>3. To unplug a lamp you should grasp (cord) +(plug) firmly and pull.</p> + +<p>4. Wire in lamp cord usually comes in sizes +16 or 18. Size 16 is the smaller (true) (false).</p> + +<p>5. In fastening wire around a terminal post +it should go around in a (clockwise) (counter-clockwise) +direction.</p> + +<p>6. When the switch on a lamp is turned off, +the electricity only goes as far as (the wall +plug) (the switch).</p> + +<p>7. An Underwriters' knot should be used +(only when there is room for it in the plug) +(whenever there is likely to be strain on the +cord, even if you have to replace the plug +with a larger one).</p> + +<h3>SUGGESTED DEMONSTRATIONS</h3> + +<p>Show how to inspect a lamp and its cord. +You might tie tags on the cord and lamp at +points of danger or failure—at the plug, +wear points next to lamp base, bad sockets.</p> + +<p>Demonstrate the process of repairing a +lamp cord, socket and plug.</p> + +<p>Make a board display of the parts of the +lamp socket showing cord attached.</p> + +<p>Make a display of the types of lamp cords +and plugs in common use.</p> + +<p>Using two lamps, one with clean bulb and +shade, the other dusty, show how the former +gives more light.</p> + +<h3>For More Information</h3> + +<p>Lamps have an interesting history. Look it +up in your local library. Ask someone from +your power supplier or electric dealer to talk +to the club about the different kinds of lamps. +Your leader has or can get additional information +on lamps, if you wish.</p> + +<div class="figcenter"> +<img src="images/p13_violation.jpg" width="250" height="188" alt="" /> +</div> + +<p><span class="pagenum">[14]</span></p> + +<p>What Did You Exhibit</p> + +<p>What Did You Demonstrate</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[15]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-4">LESSON NO. B-4</h2> + +<p class="h4">Credit Points 3</p> + +<h3><b>MAKE A TROUBLE LIGHT.</b></h3> + +<p>A handy piece of equipment in the home +and on the farm is a heavy-duty extension +cord with a shielded light and a side +outlet on it. When you want to work on the car +or tractor in the yard at night, the trouble +light is better than a flashlight. You can use +it both for light and as an extension cord. It +is safer than matches or a lantern, especially +around the garage or barn.</p> + +<p>It is easy to make a trouble light, and it +gives you good practice in electrical work. +Of course you can buy one, but you wouldn't +have the fun of making it nor would it suit +your needs. Trouble lights are not for permanent +use—they're for emergency use and +to provide light or electricity in places where +they are seldom needed. When you find a +trouble light being used as permanent wiring, +that's the place to install an outlet.</p> + +<h3>What Size Cord?</h3> + +<p>Choose the right kind of cord. What length +will be best for your various uses? A cord +too long may be bothersome to use and store. +What will be the heaviest load you are likely +to put on the cord, in amperes? Check appliances +you may want to connect to it. No. 16 +wire can carry 10 amperes safely for a distance +of 50 feet, while No. 18 can carry only +up to 7 amperes for a distance of 40 feet. +You'll want a "hard service" cord, called S, +ST, or SO-type cord by electricians. Junior +hard service cords, known as SJ, SJT, or +SJO, are fine for lighter duty.</p> + +<h3>Cord, Plug and Guard</h3> + +<p>A rubber-handled socket should be used +for safety and to withstand hard knocks. It +should have a switch on it, preferably a push +switch in a recess in the handle.</p> + +<p>The connector or attachment plug should +be of rubber or solid plastic and have a metal +cord grip fastened to it. This grip will hold +the cord firmly and prevent strain on the +terminal connections.</p> + +<div class="figcenter"> +<img src="images/p15_trouble.jpg" width="175" height="163" alt="" /> +</div> + +<p class="caption">Finished Trouble Light</p> + +<p>Get a good lamp guard. If the wire is too +light, it may bend and break the bulb when +hit or dropped. For the lamp itself, get a +rough service lamp. An ordinary lamp won't +last long with rough usage.</p> + +<h3>How to Make the Trouble Light</h3> + +<p><i>Tools Needed:</i></p> + +<p>Your 4-H electrician's kit or screwdriver, +knife and soldering iron</p> + +<p><i>Materials Needed:</i></p> + +<p>1. About 20 feet of 2-wire, No. 16 heavy +duty (hard service)</p> + +<p>2. A rubber-handled socket with switch +and a side outlet</p> + +<p>3. A shielded lamp guard</p> + +<p><span class="pagenum">[16]</span></p> + +<div class="figcenter"> +<img src="images/p16_materials.jpg" width="237" height="130" alt="" /> +</div> + +<p class="caption">Materials Needed</p> + +<p>4. A good connector plug cap, preferably +with a clamp-type grip for the cord</p> + +<p>5. A rough service lamp bulb</p> + +<p>6. Solder and flux</p> + +<p><i>Steps to Take:</i></p> + +<p>1. Remove about 2 inches of the outer +covering of cord at one end.</p> + +<p>2. Separate the wires and cut away the +filler material.</p> + +<p>3. Remove 3/4 inch of the conductor insulation +from the end of each wire and +tightly twist the strands together to +form a firm conductor. Be careful not +to cut any of the fine wires. Ends may +be soldered.</p> + +<p>4. Slide the plug in position on the cord.</p> + +<p>5. If there is no cord grip, tie the underwriters' +knot (Figure 1). If there isn't +room enough, make an "S" loop by +passing the wires around the prongs +before fastening them to the terminal +screws as explained in the next step.</p> + +<p>6. Loop the bare part of the wire around +the screw in the direction the screw +is turned to tighten (clockwise direction). +This will prevent the wires +from being forced out from under the +head of the screw as it is tightened. +Now repeat with the second wire, +wrapping it around the other prong of +the plug.</p> + +<p><i>Connecting the socket.</i></p> + +<p>1. Separate the parts of rubber-handled +socket (Figure 2).</p> + +<p>2. Prepare the other end of the cord as +in steps 1, 2, and 3 above.</p> + +<p>3. Insert the cord through the rubber +handle and socket guard.</p> + +<p>4. Tie the holding knot (underwriters' +knot) as explained in Step 5.</p> + +<p>5. Connect wires to terminal screws and +assemble the rubber-handled socket.</p> + +<p>6. Screw in the rough service lamp and +test your cord.</p> + +<p>7. Put the shielded lamp guard on the +socket and tighten the holding clamp +until it is firmly in place. You are +now ready to use or demonstrate your +trouble light.</p> + +<p>8. After you've made your trouble light, +decide on a good place to keep it where +it will be handy for use. Loop it carefully +and hang it over a wooden dowel +rather than a nail. It will last longer.</p> + +<div class="figcenter"> +<img src="images/p16_knot.jpg" width="187" height="267" alt="" /> +</div> + +<p class="caption">Figure 1 Tying an Underwriter's Knot</p> + +<p><span class="pagenum">[17]</span></p> + +<div class="figcenter"> +<img src="images/p17_fig2.jpg" width="187" height="120" alt="" /> +</div> + +<p class="caption">Figure 2 Disassembled Light</p> + +<h3>What Did You Learn?</h3> + +<p>(Underline correct answer)</p> + +<p>1. A Junior Hard Service Cord is known as +an (SO-Type) (SJO-Type) cord.</p> + +<p>2. You disconnect a cord by (jerking it from +the socket) (grasping plug and pulling it +out).</p> + +<p>3. Brass sockets are unsafe because (they +break too easily) (the exposed metal can +cause short circuits).</p> + +<p>4. Rubber-covered cord is safer for emergency +cords than fabric because (it will +stretch) (it will insulate and protect the +wires inside).</p> + +<p>5. In a trouble light (any kind of bulb will +do) (a rough service bulb is best).</p> + +<h3>Ideas for Demonstrations and Exhibits</h3> + +<p>1. Show how to make your trouble light and +a method of storing it.</p> + +<p>2. Show a safe trouble light, and an unsafe +trouble light with danger points marked.</p> + +<p>3. Show cutaway pieces of different types of +cord.</p> + +<h3>For More Information</h3> + +<p>Ask your power supplier, county highway +engineer, police official or leader to tell you +about various types of portable emergency +lights and their uses.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[18]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-5">LESSON NO. B-5</h2> + +<p class="h4">Credit Points 5</p> + +<h3><b>WHAT MAKES MOTORS RUN</b></h3> + +<p>What makes an electric motor run? Can +you make an electric motor that will +run? Certainly you can, and by doing so +you'll learn why it runs. It won't be mysterious +any more and you'll be ahead of all +the millions of people who use motors every +day and never know why or how the motor +converts electrical energy into useful +power.</p> + +<div class="figcenter"> +<img src="images/p18_makingmotor.jpg" width="212" height="200" alt="" /> +</div> + +<h3>Motors Are Magnets</h3> + +<p>You know how one end of a compass +needle always points to North. No matter +how you turn the compass, the same end of +the needle always swings to the North. The +earth itself and that small compass are +both magnets (Figure 1). Each has a North +pole and a South pole. Around the poles of +each there are magnetic fields, invisible +lines of force that attract and repel.</p> + +<div class="figcenter"> +<img src="images/p18_fig1.jpg" width="225" height="138" alt="" /> +</div> + +<p class="caption">Figure 1. The same end of the compass needle always points to the earth's magnetic North Pole.</p> + +<p>The N poles <i>repel</i> each other and so do +the S poles. The N and S poles <i>attract</i> each +other. In other words, opposite poles attract; +poles that are alike repel each other.</p> + +<p>Lay 2 bar magnets on a table side-by-side. +If both N poles are at one end, they'll +repel each other and almost flip around until +there's a N pole lying next to a S pole +(Figure 2).</p> + +<div class="figcenter"> +<img src="images/p18_fig2.jpg" width="110" height="145" alt="" /> + +</div> + +<p class="caption">Figure 2. Small bar magnets laid side by side move +so that the North pole of one is near the South pole +of the other.</p> + +<p>Now suppose we place one of the bar +magnets on the table. The other, we'll fix +on a pivot so it can spin around. This one +we'll move so its N pole almost touches the +fixed magnet's N pole. As soon as we release +it, the movable magnet will spin around +so its S pole will be near the N pole of the<span class="pagenum">[19]</span> +stationary magnet. That's an electric motor—almost.</p> + +<div class="figcenter"> +<img src="images/p19_fig3.jpg" width="175" height="125" alt="" /> +</div> + +<p class="caption">Figure 3. A movable bar magnet pivots so its South pole is near the North pole of a stationary magnet.</p> + +<p>It's not quite a motor because the rotating +magnet will just move as far as it +has to in order to get the opposite poles +together. You might be able to cause the +movable bar magnet to make turn after +turn. You could do this by turning the fixed +magnet quickly end for end. This wouldn't +be very practical as a motor.</p> + +<h3>We Can Improve It</h3> + +<p>If we could change the pole on one end of +the rotating magnet just as soon as it +reaches the attracting pole, it could make +a complete circle. In doing that, the pole +at the near end of the rotating magnet would +be repelled by the stationary magnet and +pushed away. As soon as the opposite end +of the rotating magnet would come into the +magnetic field, it would be drawn to the +stationary magnet. In order to keep the +"motor" running, we would have to constantly +change the poles at each end on +every half revolution.</p> + +<h3>We Need An Electromagnet</h3> + +<p>We can't reverse the poles on simple +bar magnets, but we can on <i>electromagnets</i>. +We can make one by wrapping a wire several +times around an iron core to form a coil. +This magnet will also have a N and a S pole +when connected to electrical current. The +big difference is that the poles can be +changed instantly by reversing the current +in the wire.</p> + +<h3>Switching Poles Automatically</h3> + +<p>The rotating electromagnet will have to +be connected to the 2 wires through which +we pass the current. Since it's rotating on +a center shaft, we can't have a solid connection. +Instead we have to extend the +wires from the coil out along the shaft and +let the electric contact be made with +brushes which touch the wires along the +shaft.</p> + +<div class="figcenter"> +<img src="images/p19_fig4.jpg" width="250" height="150" alt="" /> +</div> + +<p class="caption">Figure 4. A rotating electromagnet changes poles as contacts are made first one way, then the other.</p> + +<p>This is a simple way to reverse the current +in the coil of the electromagnet.</p> + +<h3>Increasing Efficiency</h3> + +<p>Instead of using only one pole of a +stationary magnet, we can use both. This +is done by shaping the stationary magnet +around the path of the rotating electromagnet. +This way we have the benefit of +the attracting and repelling forces from +both poles. The effect is doubled.</p> + +<p>We can also wrap wires around this +circular iron and make an electromagnet +of it. But when we wire this magnet we +use no brushes because we want the current +to flow in one direction only.</p> + +<p>The stationary electromagnet is called +the <i>field</i>. The rotating electromagnet is +the <i>armature</i>.</p> + +<p><span class="pagenum">[20]</span></p> + +<h3>WHAT TO DO: Make A Motor</h3> + +<p><i>Tools Needed:</i></p> + +<p>Pocket knife, hammer, vise (or 2 pairs +of pliers).</p> + +<p><i>Materials Needed</i>:</p> + +<pre> +1 roll of No. 24 enameled wire +1 roll of electrician's tape +3 - 4" (20-penny) nails +4 - 2-1/2" (8-penny) nails +4 - 3" brads (10 penny) +Wood board for motor base +2 staples or 4 small brads +2 tacks +2 - 3 volt dry cell batteries (or a 6 +volt transformer). +</pre> + +<h3>Step No. 1-Armature</h3> + +<div class="figcenter"> +<img src="images/p20_step1a.jpg" width="125" height="95" alt="" /> +</div> + +<p>Wrap about 1-1/2" of a +4" nail with two layers of +tape. This will be the +shaft.</p> + +<div class="figcenter"> +<img src="images/p20_step1b.jpg" width="125" height="130" alt="" /> +</div> + +<p>The iron core will be +made of two pairs of +2-1/2" nails. Wrap tape +around each pair with +heads and points alternated.</p> + +<div class="figcenter"> +<img src="images/p20_step1c.jpg" width="125" height="100" alt="" /> +</div> + +<p>Center both pairs on each +side of the shaft. Place +them about 1" from the +head of the shaft nail. +Wrap them together with +two layers of tape from +tip to tip.</p> + +<div class="figcenter"> +<img src="images/p20_step1d.jpg" width="125" height="85" alt="" /> +</div> + +<p>Start at the shaft and wind +No. 24 enameled wire to +one end and back. Then +do the same on the other +end. Always wind in the +same direction. Leave 6" +of spare wire at start and +finish.</p> + +<h3>Step No. 2-Commutator</h3> + +<div class="figcenter"> +<img src="images/p20_step2a.jpg" width="237" height="112" alt="" /> +</div> + +<p>Scrape all insulation off the ends of the wire. +Bend the bare ends back and forth as +shown. Lay them flat over the taped shaft-one +on each side of the shaft.</p> + +<div class="figcenter"> +<img src="images/p20_step2b.jpg" width="137" height="105" alt="" /> +</div> + +<p>Hold the commutator down with narrow +strips of tape. Wrap tightly near the core +and at the opposite end.</p> + +<h3>Step No. 3-Field</h3> + +<div class="figcenter"> +<img src="images/p20_step3a.jpg" width="112" height="95" alt="" /> +</div> + +<p>Make the core by bending +two 4" nails in the middle +at right angles. Space the +heads about 3" apart to +form a horseshoe. Wrap +together with two layers +of tape.</p> + +<div class="figcenter"> +<img src="images/p20_step3b.jpg" width="200" height="153" alt="" /> +</div> + +<p>Wind about 400 turns of wire around the +center. Leave 4" of spare wire at start +and finish. Attach to wood base with staples +at each end of the wire. Small brads, bent +over, will do just as well.</p> + +<p><span class="pagenum">[21]</span></p> + +<h3>Step No. 4—Armature Supports and Brushes</h3> + +<div class="figcenter"> +<img src="images/p21_armature.jpg" width="237" height="182" alt="" /> +</div> + +<p>Scrape the insulation from the ends of two +6" pieces of wire. Tack them to the base +and bend them as shown to make brushes.</p> + +<p>Drive two pairs of 3" brads into the base +about 3-1/4" apart and in a line midway +between the field poles. Wrap wire around +the supports to form armature bearings.</p> + +<p>Scrape insulation off ends of wire from the +field. Connect one end to a brush wire.</p> + +<div class="figcenter"> +<img src="images/p21_assembled.jpg" width="212" height="222" alt="" /> +</div> + +<p><i>Assemble As Shown</i></p> + +<p>Adjust the position of commutator and +tension of brushes against it for best operation.</p> + +<p>Take the armature off the motor and +connect the commutator wires to a dry +cell battery. Test the polarity of each end +of the armature with a compass. Switch +the connections on the commutator and +test again. See how the compass needle +changes direction?</p> + +<p>With the armature still off, connect the +field coil directly to the dry cell. Test the +polarity of each end of the field with the +compass. How can you reverse the polarity? +Try it. It's easy.</p> + +<p>Reassemble the motor again and start +it. Push the field poles slightly out of +alignment with the turning armature. What +happens to the motor's speed? Can you +tell why?</p> + +<p>This time, push the field poles completely +out of the way. Test the polarity of +the armature as you slowly turn it by hand. +Do you see what happens and why it does?</p> + +<p>Try to reverse the direction of rotation +of your motor by reversing the connections +at the battery. What happens? Can you explain +why?</p> + +<h3>Demonstrations You Can Give</h3> + +<p>Make a display board showing the parts +of the toy motor and explain how each part +works compared with the parts of a commercial +motor.</p> + +<h3>For Further Information</h3> + +<p>There are several other types of toy +motors you can build. Your club leader or +power supplier can help you find information +about them.</p> + +<p><span class="pagenum">[22]</span></p> + +<p>1. Did your toy motor run?</p> + +<p>2. Did your motor speed up or slow down when you pushed the field poles out of line?</p> + +<p>Why?</p> + +<p>3. What happens to the magnetic polarity of the armature when you turn it slowly by hand and +check it with a compass?</p> + +<p>4. How can you reverse the direction of rotation of your toy motor?</p> + +<p>Is there another way too?</p> + +<p>What is it?</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[23]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-6">LESSON NO. B-6</h2> + +<p class="h4">Credit Points 3</p> + +<h3><b>TAKING CARE OF ELECTRIC MOTORS</b></h3> + +<p>Through the magic of electric motors, +much of our work is done faster and +better at lower cost than we could do it +without the help of the electric motor. +People who use motors and treat them properly +have much more time for other work +and for leisure time activities. A 1/4-horsepower +motor running quietly and steadily +hour after hour will do the work of one +man, and operate all day for about 5 cents +without tiring. On many jobs it will work +without "supervision", turning on and off +automatically, as required. It does this on +water pumps, in heating and cooling units, +and on fans and similar appliances.</p> + +<div class="figcenter"> +<img src="images/p23_motors.jpg" width="187" height="167" alt="" /> +</div> + +<p>All that a motor needs to do its work is +electricity and a little care. Let's see what +you can do to give proper care to motors in +your home and on your farm.</p> + +<h3>You'll Need</h3> + +<p>A light oil (SAE 10) for motors of less +than one horsepower and a slightly heavier +oil (SAE 20) for larger motors. See if you +need grease for cups which may be on large +motors. If so, be sure you use ball-bearing +grease and not ordinary cup grease. Cotton +waste or clean rags will be needed for wiping +off the motors, and a tire pump or +vacuum cleaner for blowing out the dust or +dirt.</p> + +<div class="figcenter"> +<img src="images/p23_instrux.jpg" width="135" height="188" alt="" /> +</div> + +<p class="caption">Some motors have instructions for oiling on the name-plate.</p> + +<h3>WHAT TO DO</h3> + +<p>1. First, make a list of all the electric +motors that work for your home. You may +wish to make a separate list for your farm +buildings. You'll probably be surprised at +how many there are. Don't forget the sewing +machine, the refrigerator, the freezer, +the vacuum cleaner and other small but important +motors. Don't touch any motor that +is running. Disconnect them before you +touch them.</p> + +<p>2. Make a motor service chart with +columns headed: Use, Location, Horsepower, +Volts, Amperes, Service Required, +Date Serviced and What was Done. (See +sample) Then list all the motors that require +any servicing. Some will have the instructions +on the motor or appliance; the +instruction booklet that came with the +motor or appliance will also tell what servicing +is required.</p> + +<p><i>Step 1.</i> Plan the job. Start with the +motors in the home. Then you can care for +the motors on the farm.</p> + +<p><span class="pagenum">[24]</span></p> + +<p><i>Step 2.</i> Be sure that any motor on which +you are going to work is disconnected. +Then wipe the outside case clean with a +cloth. If the motor has openings in the end, +use a vacuum cleaner to suck out dust, dirt +or chaff. A tire pump may also be used to +blow out this dirt. If you use compressed +air, be sure the pressure is not high as it +may damage wiring inside the motor. Dust-proof +motors should be used in dusty or +dirty places.</p> + +<p><i>Step 3.</i></p> + +<div class="figcenter"> +<img src="images/p24_step3.jpg" width="175" height="125" alt="" /> +</div> + +<p class="caption">If there are oil holes, oil according to the manufacturer's instructions.</p> + +<p>If there are no instructions, remember +a little oil goes a long way as far as motors +are concerned. Motors of less than one +horsepower require only 3 or 4 drops (not +squirts) of oil every 3 or 4 months if the +motor is used frequently. Too much oil +can damage the motor. It spoils the insulation.</p> + +<p>If there are no oil holes or grease cups +on the motor, it is probably lubricated by +means of grease sealed in the bearings at +the factory, or it may use greaseless bearings, +and does not need to be oiled or +greased periodically. Indicate on your +chart all motors which need periodic care +and see that it is given according to +schedule.</p> + +<p>Wipe away any excess oil or grease. Be +sure oil holes are capped or covered.</p> + +<p><i>Step 4.</i> Reconnect motor and run for a +moment.</p> + +<p><i>Step 5.</i> Record on the chart the date you +serviced the motor and what was done.</p> + +<h3>What Did You Learn?</h3> + +<p>How many motors are there in your home? +______ On the farm? ______</p> + +<p>How many motors need regular oiling or +grease? ______</p> + +<p>How many are less than one-horsepower? ______</p> + +<p>SAE Oil ______ is used to oil motors up to +1/2 horsepower. How much oil?______</p> + +<p>SAE Oil______ is used for larger motors.</p> + +<h3>Demonstrations You Can Give</h3> + +<p>1. Show how to clean a small motor.</p> + +<p>2. Explain proper lubrication of motors.</p> + +<p>3. Using the chart prepared in this work +sheet, give a talk about the motors that +work for you-the job each one does, +which ones need oil or grease, which +need no attention, and why, etc.</p> + +<p>4. Use a homemade toy motor to explain +"what makes motors run."</p> + +<p>5. Show proper way to replace worn cord +on a small motor.</p> + +<h3>For Further Information</h3> + +<p>Ask your county Extension agent or 4-H +leader for more literature on motors. They +can help you obtain a film or a speaker +such as a power supplier, a local electric +dealer, or electrical contractor to discuss +motors.</p> + +<p>Also visit your public library and see a +science teacher for more information on +motors.</p> + +<p><span class="pagenum">[25]</span></p> + +<p class="spacer"> </p> + +<h3>ELECTRIC MOTORS SERVICE CHART Sample</h3> + +<p class="h5">Use a table like the following to list the motors around your farm and home.</p> + +<div class="center"> +<table border="2" cellpadding="10" cellspacing="0" summary="Motor Service Table"> + <tr> + <td class="tdl">Motor Use</td> + <td class="tdl">Location</td> + <td class="tdl">H.P.</td> + <td class="tdl">Volts</td> + <td class="tdl">Amps.</td> + <td class="tdl">Service Needed</td> + <td class="tdl">Date Serviced and what was done</td> + </tr> + <tr> + <td class="tdl">Food Mixer</td> + <td class="tdl">Kitchen</td> + <td class="tdl">1/6</td> + <td class="tdl">120</td> + <td class="tdl">4.4</td> + <td class="tdl">Clean & Oil; cord needs repair</td> + <td class="tdl">9/1-Cleaned w/cloth. Oiled w/#10 Oil; repaired cord</td> + </tr> + <tr> + <td class="tdl">Tool Grinder</td> + <td class="tdl">Farm Shop</td> + <td class="tdl">1/4</td> + <td class="tdl">120</td> + <td class="tdl">5.8</td> + <td class="tdl">Clear, oiling; Have switch repaired</td> + <td class="tdl">10/6-Cleaned w/vacuum; Oiled, #10 oil. 10/20. Had switch repaired</td> + </tr> + <tr> + <td class="tdl">Pump</td> + <td class="tdl">Pump house</td> + <td class="tdl">1/3</td> + <td class="tdl">120</td> + <td class="tdl">7.2</td> + <td class="tdl">Oiling, cleaning</td> + <td class="tdl">9/26-Cleaned w/tire pump; oiled w/10 oil</td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> +</table></div> + +<hr class="chapter" /> + +<p><span class="pagenum">[26]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-7">LESSON NO. B-7</h2> + +<p class="h4">Credit Points 4</p> + +<h3>READING THE ELECTRIC METER</h3> + +<p>There is no question but what electricity +is one of the lowest cost services in +the home and on the farm. A few pennies +worth of electricity will provide the power to +run machines that take the place of a man or +of several men working all day. However, we +all like to know what things cost.</p> + +<p>Sometime you may have to decide between +different methods—man, horse, gasoline engine +or electric motor power. Then you'll +want to know how to figure the cost of electricity, +as well as the cost of the original +equipment. First of all, you should know +how to read an electric meter.</p> + +<h3>Reading a Meter</h3> + +<p>Electric meters read in kilowatt hours, just +as a water meter reads in gallons and a gas +meter in cubic feet. A kilowatt hour is the +electrical energy consumed by 1000 watts of +electricity used for one hour. Ten 100-watt +light bulbs burning for one hour would use +one kilowatt-hour—one kwh.</p> + +<div class="figcenter"> +<img src="images/p26_fig1.jpg" width="175" height="98" alt="" /> +</div> + +<p class="caption">Figure 1. Some meters give the reading directly, like the mileage total on a speedometer.</p> + +<p>Some meters are read directly, as shown +in Figure 1. The more common type has four +dials which are read from right to left—just +the opposite from the way things are usually +read. The hand on the extreme right turns +clockwise, the next hand turns counter-clockwise, +the next clockwise; the last hand on +the left turns counter-clockwise.</p> + +<div class="figcenter"> +<img src="images/p26_readingmeter.jpg" width="212" height="180" alt="" /> +</div> + +<p>The first dial on the right can register +up to 10 kilowatt-hours; the second up to 100 +kwh; the third, to 1000 kwh; the fourth, to +10,000 kwh. After that, the meter starts over +again. To take a reading you must read all +four dials of the meter, from right to left.</p> + +<div class="figcenter"> +<img src="images/p26_fig2.jpg" width="237" height="127" alt="" /> +</div> + +<p class="caption">Figure 2. Meter dials are read from right to left.</p> + +<p>To read each dial, you use the number +last passed by the dial hand. This may not be +nearest the hand. For instance, if the pointer +has passed 6 and is almost on 7, you read it +as 6. Write down the figures in the same +order you read the dial, from right to left. +Practice reading the meters shown in Figure +3 on the following page.</p> + +<h3>What's Your Electric Bill?</h3> + +<p>Meters aren't set back each month when +the meter reader comes around. The difference<span class="pagenum">[27]</span> +in the readings from one month to the +next shows how many kilowatt-hours have +been used. If you know your electric rates, +you can figure your bill by yourself. Your +power supplier will furnish you with a rate +schedule on request.</p> + +<div class="figcenter"> +<img src="images/p27_fig3.jpg" width="250" height="247" alt="" /> +</div> + +<p class="caption">Figure 3. See if you can read the above correctly. The answers are shown in a box on the next page.</p> + +<p>It will be interesting to you to find out +how much it costs to operate the various +electric appliances in your home. A sample +rate schedule is shown in Figure 4.</p> + +<div class="figcenter"> +<img src="images/p27_fig4.jpg" width="225" height="167" alt="" /> +</div> + +<p class="caption">Figure 4. Sample rate schedule. Note that as the use of electricity increases, the average cost per kwh is reduced.</p> + +<h3>Estimating Operating Costs</h3> + +<p>To find the cost of operating any single +appliance, three steps are necessary:</p> + +<p>1. Learn the wattage of the appliance.</p> + +<p>2. Estimate how many hours the appliance +is used.</p> + +<p>3. Find its operating cost.</p> + +<p><i>To Find Wattage:</i></p> + +<p>Watts, you know, are the measure of +electrical power. They are the product of +voltage (pressure) times amperes (rate of +flow). Volts times Amps equals Watts. The +nameplate on the appliance will give the voltage +required for proper operation as well as +either amperage or watts. If it gives wattage, +you have the information you want. Otherwise +you must multiply volts times amps to +get the wattage. When voltage is given as +110-120, use 120 as your voltage. 120 volts +is nominal today.</p> + +<p><i>How Much Will You Use?</i></p> + +<p>Now that you know the wattage of the appliance, +multiply this figure by number of +hours the equipment operates in one day. +Divide this by 1000 to get the kwh. Now multiply +the result by the number of days the +appliance is used each month. This tells you +the number of kwh used by the appliance during +the month.</p> + +<div class="inset26 topbox"> +<p class="h5">Example No. 1</p> +<p class="margin20"><i>Yard Light:</i> 300-watt lamp<br /> +<br /> +Amount of use: 3 hours per night.<br /> +<br /> +Multiply lamp wattage times hours of use +per night to get watt-hours per night.<br /> +<br /> +300 times 3 = 900 watt-hours per night.<br /> +<br /> +Divide watt-hours by 1000 to get kwh per night.<br /> +<br /> +900 divided by 1000 = .9 kwh per night.<br /> +<br /> +Multiply kwh per night times 30 to get kwh per month.<br /> +<br /> +.9 times 30 = 27 kwh per month.<br /> +<br /> +If the yard light is used 3 hours per night, it consumes 27 kwh per month. +</p> +</div> + +<p><span class="pagenum">[28]</span></p> + +<p class="spacer"> </p> + +<div class="inset26 topbox"> +<p class="h5">Example No. 2</p> + +<p class="margin20"><i>Coffee Maker</i>: 120 volts, 550 watts (from nameplate)<br /> +<br /> +Amount of use: 1/2 hour per day.<br /> +<br /> +Multiply wattage of coffee maker times +hours of use per day to get watt-hours per day.<br /> +<br /> +550 times 1/2 hour = 275 watt-hours per day.<br /> +<br /> +Divide watt-hours by 1000 to get kwh per day.<br /> +<br /> +275 divided by 1000 = .275 kwh per day.<br /> +<br /> +Multiply kwh per day times 30 to get kwh per month.<br /> +<br /> +.275 times 30 = 7.250 kwh per month.<br /> +<br /> +If the coffee maker is used l/2 hour daily, +it consumes 7.25 kwh per month. +</p> +</div> + +<p><i>Calculate Operating Cost Per Month</i></p> + +<p>Now that you know the number of kilowatt +hours an appliance uses, go to your rate +schedule and your electric bill to see what the +average kwh costs. Find the average cost of +1 kwh by dividing the amount of your bill by +the total number of kwh used in a month.</p> + +<p class="hang"> +<i>Example</i>: 410 kwh used.<br /> +$14.35 total monthly bill<br /> +<br /> +Average cost per kwh equals $14.35 divided +by 410 kwh-3-1/2 cents per kwh.</p> + +<p>Therefore, the cost of operating the coffee +maker for a month would be 3-1/2 cents +times 7.25 kwh—25.4 or 25 cents. Cost of +operating the yard light would have been 94.5 +or 95 cents a month.</p> + +<div class="inset20 topbox"> +<p class="margin20">(a) 6357 nbsp; (b) 1963 (c) 8996 +<br /><br /> +Correct answers to the meter readings +shown on the preceding page. +</p> +</div> + +<h3>Adding Low Cost Helpers</h3> + +<p>You can see, by looking at your rate schedule, +that the average cost per kwh gets lower +as you use more electricity. To find the +cost of operating additional electrical equipment, +the cost per kilowatt hour is found from +the last "step" in the bill—the lowest cost +per kwh of the electricity you're now using. +Sometimes power suppliers give special rates +for such equipment as electric water heaters.</p> + +<h3>WHAT TO DO: Find the Cost +of Operating Electrical Equipment</h3> + +<p>Make and fill in the blanks of a chart +showing the electrical equipment you have +and the operating costs per month.</p> + +<p>Make a chart for the home (refer to chart +one). Show the probable operating cost of +equipment you might add to what you now +have.</p> + +<h3>Demonstrations You Can Give</h3> + +<p>Show how to read a meter, making one +with plywood or cardboard. Dials can be +painted on the main board. Arrows can be +attached so they will revolve to give different +readings.</p> + +<p>Show how to find the wattage of various +types of equipment.</p> + +<p>Show how to figure the cost of the average +kwh in a home.</p> + +<h3>For Further Information</h3> + +<p>Your leader can get additional material +for you or you may want to have someone +from your power supplier talk to your club, +telling about meters, how they work and how +they are regularly checked for accuracy.</p> + +<p><span class="pagenum">[29]</span></p> + +<p class="h4">Chart One-THE HOME</p> + +<div class="center"> +<table border="2" cellpadding="10" cellspacing="0" summary="Home Wattage Chart"> + <tr> + <td class="tdc">Column No.</td> + <td class="tdc">1.</td> + <td class="tdc">2.</td> + <td class="tdc">3.</td> + <td class="tdc">4.</td> + <td class="tdc"> </td> + </tr> + <tr> + <td class="tdl">Item</td> + <td class="tdl">Wattage Rating</td> + <td class="tdl">Hours Used per Month</td> + <td class="tdl">KWH per Month<br />(col. 1 x 2) / (1000)</td> + <td class="tdl">Cost per Month<br />(Col. 3 x av.kwh cost)</td> + <td class="tdl">Remarks</td> + </tr> + <tr> + <td class="tdl">Electric Iron</td> + <td class="tdl">1100</td> + <td class="tdl">30</td> + <td class="tdl">33</td> + <td class="tdl">.80</td> + <td class="tdl"> </td> + </tr> + <tr> + <td class="tdl">Stove</td> + <td class="tdl">880</td> + <td class="tdl">60</td> + <td class="tdl">52.8</td> + <td class="tdl">1.21</td> + <td class="tdl">(Special rate.)</td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> + <tr> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + <td class="tdl"> </td> + </tr> +</table></div> + +<hr class="chapter" /> + +<p><span class="pagenum">[30]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-8">LESSON NO. B-8</h2> + +<p class="h4">Credit Points 3</p> + +<h3><b>IRONING IS FUN WITH THE MODERN HAND IRON</b></h3> + +<p>When you are getting ready to go to +school or to a party, it probably gives +you a good feeling to put on a clean, +freshly-ironed skirt, blouse or dress. But +did you ever think about the electric iron +that helps so much to give you that well-dressed +feeling? When you were younger, +you may have had a play iron and pretended +to iron your doll's dresses. Now +you are old enough to learn about real +irons—the different kinds of irons, how +the iron heats, the kind of cord needed, the +type of outlet necessary, how to use safety +rules when you iron, and even how to help +with the ironing.</p> + +<div class="figcenter"> +<img src="images/p30_ironing.jpg" width="172" height="249" alt="" /> +</div> + +<h3>Important Things to Know</h3> + +<p>There are many different irons, but the +two kinds most important for you to know +about now are the regular dry iron and the +combination steam-and-dry iron.</p> + +<div class="figcenter"> +<img src="images/p30_thermostat.jpg" width="237" height="79" alt="" /> +</div> + +<p class="caption">The thermostat keeps the iron at an even temperature.</p> + +<p>It isn't weight alone that makes an iron +do its job, but the heat of the iron. The heat +is given off in the sole plate. The automatic +iron has what is called a <i>thermostatic</i> control +which holds the temperature of the +iron at the heat you want. Some clothes +need to be ironed with a very hot iron, +while others need only to be pressed lightly +with a cool iron. The thermostat keeps +the iron at an even temperature after you +set it for the heat you want. The thermostat +is the heart of the iron.</p> + +<p>Take a look at the iron used in your +home. It isn't heavy to lift, and has a +handle that fits your hand easily. It looks +graceful and has a smooth bottom, called +the sole plate. And it may have a narrow, +pointed tip which is helpful in ironing pleats, +corners and gathers.</p> + +<div class="figcenter"> +<img src="images/p30_soleplate.jpg" width="175" height="165" alt="" /> +</div> + +<p class="caption">Your iron has a smooth bottom called the sole plate.</p> + +<p><span class="pagenum">[31]</span></p> + +<h3>The Iron and Safety</h3> + +<p>If you are going to learn to do some +ironing yourself, the most important thing +for you to remember is SAFETY. You +should read all about the iron first in the +instructions which came with it.</p> + +<p>Never use an iron carelessly. Remember +the safety rules:</p> + +<p>1. An iron should never be left even for +a few minutes without being disconnected. +Turn off by removing the plug from the outlet, +or by turning the control lever to "off."</p> + +<div class="figcenter"> +<img src="images/p31_plug.jpg" width="130" height="110" alt="" /> +</div> + +<p class="caption">Take hold of the plug—not the cord—when you disconnect +it from the outlet.</p> + +<p>2. Let the iron cool before putting it +away.</p> + +<p>3. Wrap the cord carefully around the +iron after it is cold.</p> + +<p>4. Always stand the iron where it will +not fall off on a child or pet or your own +toes.</p> + +<h3>WHAT TO DO: Learn About Your Iron</h3> + +<p>Materials Needed: An automatic iron, some +old play clothes, towels, napkins or handkerchiefs, +and an ironing board.</p> + +<p>Steps to Take:</p> + +<p>1. Watch an experienced person iron.</p> + +<p>2. Ask questions about what clothes +need to be sprinkled.</p> + +<p>3. Study the thermostat settings on the +dial or indicator.</p> + +<div class="figcenter"> +<img src="images/p31_dial.jpg" width="133" height="110" alt="" /> +</div> + +<p class="caption">Most irons have a dial to set for the proper heat for different fabrics.</p> + +<p>4. Ask about the kind of fabric each piece +of clothing is—cotton, linen, silk, nylon, +etc.—and why the iron should be at high +heat for some, cooler for others.</p> + +<p>5. Set the thermostat for the amount of +heat needed, and with an older person +watching you, iron some handkerchiefs, +napkins, bath towels, and a pair of play +shorts or blue jeans.</p> + +<p>6. During a month iron some of these +articles for your family, keeping a record +of how many you do and what they were.</p> + +<p>7. Take care of your iron. Be responsible +for storing it.</p> + +<div class="center"> +<table border="2" cellpadding="3" cellspacing="0" summary="Ironing Log"> +<tr><td class="tdc">Date</td><td class="tdc">No. Aricles Ironed</td><td class="tdc">Type of Article</td><td class="tdc">Stored Iron Properly<br />(check)</td></tr> +<tr><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td></tr> +<tr><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td></tr> +<tr><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td></tr> +<tr><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td></tr> +<tr><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td><td class="tdc"> </td></tr> +</table></div> + +<p class="spacer"> </p> + +<p><span class="pagenum">[32]</span></p> + +<h3>IRONING IS FUN</h3> + +<p>1. I (use) (do not use) an adjustable ironing Board at home. If I do, I adjust it to the height +that just clears my knees easily as I sit in a comfortable chair. Yes No</p> + +<p>2. There are three kinds of irons usually used—dry iron, steam iron or a combination steam +or dry iron. I use a —— iron.</p> + +<p>3. I (have) (do not have) the instruction book. (If you do, read about the iron.) I know the +iron's parts by their correct names. They are——.</p> + +<p>4. I disconnect the iron if I leave it even for only a minute. This is a safety measure as fires +have been known to start from irons left connected. Yes No</p> + +<p>5. I take hold of the plug—not the cord—when disconnecting the iron. Yes No</p> + +<p>6. I wait until the iron is cold before wrapping the cord around the handle and storing the iron +because——.</p> + +<p>7. Most irons have a thermostatic control. The iron I am using has settings for——.</p> + +<p>8. The purpose of the thermostat is——.</p> + +<p>9. These fabrics need high temperature.——</p> + +<p>These fabrics need medium temperature.——</p> + +<p>These fabrics need low temperature.——</p> + +<p>10. These fabrics need sprinkling.——</p> + +<p>11. The heat and smoothness of the sole plate smoothes the wrinkles. Pushing down on the +handle or moving the iron rapidly only makes ironing hard work. I will iron slowly and +steadily arranging and moving the garment with the left hand while guiding the iron with +the right hand. (Or the other way for the left handed.) Yes No</p> + +<p>12. I have watched an experienced person iron. Yes No</p> + +<p>13. I have practiced on handkerchiefs, napkins and pillow cases.</p> + +<p>14. Here is my record of ironing for one month</p> + +<p><span class="pagenum">[33]</span></p> + +<div class="inset26 topbox"> +<p> +<br /> +<br />Month____________</p> + +<p class="right">Your Name _____________________</p> +<br /> +<p>Date I have ironed:<br /> +_____________________________________________________<br /> + | <br /> + | <br /> + | <br /> + | <br /> + | <br /> + | <br /> + | <br /> + | <br /> +</p> +</div> + +<p><span class="pagenum">[34]</span></p> + +<p class="spacer"> </p> + +<h3>Demonstrations You Can Give</h3> + +<p>1. Show a dry iron and a steam-and-dry +iron. Tell the difference between them and +when each is to be used.</p> + +<p>2. Display garments that look nice because +they have been ironed properly, and +those that have been ironed improperly. +Explain about the heat, thermostat, type of +iron and why results differ.</p> + +<h3>For More Information</h3> + +<p>At a club meeting ask a parent to give a +demonstration of ironing different articles. +Some power suppliers or dealers have +people who will demonstrate the proper way +to iron, and how to care for irons.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[35]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-9">LESSON NO. B-9</h2> + +<p class="h4">Credit Points 2</p> + +<p class="h3"><b>LET'S BE FRIENDS WITH ELECTRICITY +Plan a Hazard Hunt</b></p> + +<p>Electricity can be your important lifelong +friend and helper, so you will want to +know all you can about it and how to treat it +properly. However, careless and improper +use of electricity can do a lot of harm. Used +properly, and treated with respect, electricity +can do wonderful things to help you every +day in many ways.</p> + +<p>For safe and proper use of electricity, +all wiring, fittings, insulation, cords and +plugs must be in good condition. You can be +a detective and track down defects in any +such type of electrical equipment that you +may be using in your home or on your farm.</p> + +<p>When you find anything that is wrong, and +know where it is, and know what to do about +it, you can very likely correct the condition +yourself, such as replacing a worn extension +cord with a new one. If you find defects in +permanent wiring, or some places where +wires are bare or terminals are needed, you +should tell your parents about them.</p> + +<p>SAFETY FIRST, remember, should always +be on your mind when working with +anything electrical.</p> + +<h3>WHAT TO DO:</h3> + +<p><i>1. Have A Hazard Hunt</i></p> + +<p>Go on a Hazard Hunt to see how many +electrical hazards you can find. Look for +defects such as broken insulation, worn +cords, splices that are not properly soldered +and taped, loose connections, or switches +that aren't working properly.</p> + +<p>There are many ways to have a Hazard +Hunt. Choose the method that will be the +most fun. Use the Hazard Hunt Guide in this +outline to check your home, and other buildings. +Maybe you'll want to have a friend help +check your home, then you help him check +his. Or, why not give each member of your +family a Hazard Hunt Guide and have a contest? +Parents may want to team up against +you and other younger members of your +family to see which team can find the most +electrical hazards in some set time—say 30 +minutes.</p> + +<p>Have a Hazard Hunt Committee in your +club check all member's homes and buildings +and report its findings at the next club +meeting.</p> + +<p><i>To Make It More Fun</i></p> + +<p>1. Put a hazard tag, like the one shown, +(Figure 1) by each hazard that is found. +Leave it until the hazard is corrected. +Have another contest to see which member +of the family corrects the most +hazards.</p> + +<div class="figcenter"> +<img src="images/p35_fig1.jpg" width="127" height="162" alt="" /> +</div> + +<p class="caption">Figure 1</p> + +<p>2. Report on your Hazard Hunt at the next +club meeting. Tell about the Hazards +found, and what you have done or plan to +do about them.</p> + +<p>3. Suggest that the entire club have an Electric +Hazard Hunt at your club meeting +places or any community building. This +could be part of one meeting.</p> + +<p><span class="pagenum">[36]</span></p> + +<p>4. Have a contest between two teams in the +club to see which team can get the most +homes in your community checked by the +Hazard Hunt Guide. Losers could give a +party for the winners.</p> + +<p><i>2. Get Others Interested</i></p> + +<p>Promote a community Electric Hazard +Hunt. Enlist the support of power suppliers, +electric supply and equipment dealers, +schools, newspapers, radio and television +stations.</p> + +<p><i>What To Look For</i></p> + +<p>Make a complete tour of your home and +other buildings and see how many hazards +you can locate. When you find a hazard, put +a tag near it to mark it.</p> + +<div class="inset20 topbox"> +<h3>SAFETY TIPS</h3> + +<p class="margin20">Put hazard tags <i>near</i> the hazard +but <i>not</i> directly on broken or frayed +wires, insulators, fittings, or other +wiring equipment. Do not touch them +either. Badly-frayed wires should be +disconnected immediately from the +power supply. In this way, you will +not expose yourself to shock by accidentally +touching an exposed live +wire that may be carrying current.</p> +</div> + +<h3>4-H Electric Hazard Hunt Guide</h3> + +<p><i>Wiring and Protective Devices</i></p> + +<p>1. Cable or conduit splices not +in boxes——</p> + +<p>2. Cable or conduit not securely +clamped in boxes——</p> + +<p>3. Conduit or armored cable not +properly grounded——</p> + +<p>4. Cracked or broken insulators +(Figure 2)——</p> + +<p>5. Wire not completely covered +with insulation——</p> + +<p>6. Worn insulation on wire——</p> + +<div class="figcenter"> +<img src="images/p36_fig2.jpg" width="115" height="183" alt="" /> +</div> + +<p class="caption">Figure 2</p> + +<p>7. Old unused wiring not yet +removed——</p> + +<p>8. Outlets, junction and switch +boxes not securely fastened +and covers not in place——</p> + +<p>9. Switches not working properly +(sparks fly as switch is flipped) +(Figure 3)——</p> + +<p>10. Fuses not of proper ampere +rating for circuit——</p> + +<p>11. Extension cord used in place +of permanent wiring——</p> + +<p>12. Pull chain socket without an +insulating link in the chain——</p> + +<p>13. Pull chain socket near plumbing +fixtures or where hands +may be wet or one may stand +in water——</p> + +<div class="figcenter"> +<img src="images/p36_fig3.jpg" width="145" height="205" alt="" /> +</div> + +<p class="caption">Figure 3</p> + +<p><span class="pagenum">[37]</span></p> + +<p>14. No moisture-proof cords for +outside weather conditions or +heavy rubber cords for +motors and motor driven +appliances</p> + +<p><i>Lighting</i></p> + +<p>1. Fixtures in farm buildings +installed so that they might +be easily damaged</p> + +<p>2. Lights in haymows and other +dusty locations not protected +by dustproof globes</p> + +<p>3. Outside sockets not waterproof</p> + +<p>4. Heat lamps not properly supported +by non-current carrying +wire, chains, or brackets +(Figure 4)</p> + +<p>5. Light bulbs not frosted, +shaded, or placed so that light +is diffused to prevent glare</p> + +<div class="figcenter"> +<img src="images/p37_fig4.jpg" width="177" height="187" alt="" /> +</div> + +<p class="caption">Figure 4</p> + +<p><i>Auxiliary Wiring</i></p> + +<p>1. Outlets overloaded—in other +words, "octopus wiring"</p> + +<p>2. Extension cords placed under +rugs</p> + +<p>3. Extension cords run through +doorways (Figure 5)</p> + +<div class="figcenter"> +<img src="images/p37_fig5.jpg" width="185" height="155" alt="" /> +</div> + +<p class="caption">Figure 5</p> + +<p>4. Extension cords or lamp +cords should use underwriters' +knot (Figure 6)</p> + +<div class="figcenter"> +<img src="images/p37_fig6.jpg" width="165" height="113" alt="" /> +</div> + +<p class="caption">Figure 6</p> + +<p>5. Plug connections fuzzy (Figure +7)</p> + +<div class="figcenter"> +<img src="images/p37_fig7.jpg" width="172" height="112" alt="" /> +</div> + +<p class="caption">Figure 7</p> + +<p>6. Extension cords run over +heaters or radiators</p> + +<p>7. Extension cords, or appliance +or lamp cords, worn or frayed</p> + +<p>8. Heating appliances without +regular asbestos covered +wire</p> + +<p>9. Open sockets or outlets +where a baby or small child +might stick a finger or metal +toy</p> + +<p><span class="pagenum">[38]</span></p> + +<p>10. Broken plugs (Figure 8)——</p> + +<p>11. Loose prongs on appliance +or lamps plugs——</p> + +<div class="figcenter"> +<img src="images/p38_fig8.jpg" width="165" height="113" alt="" /> +</div> + +<p class="caption">Figure 8</p> + +<h3>How Many Hazards Did You Find?</h3> + +<p>Make a chart listing the hazards, their +locations and what you did about them. Make +your own chart and list what you find.</p> + +<h3>Demonstrations You Can Give</h3> + +<p>Show and tell others how to have a Hazard +Hunt.</p> + +<h3>For Further Information</h3> + +<p>Check with your leader, then ask your +power supplier or a local electrician to tell +you about safe electrical wiring, connections +and fixtures.</p> + +<div class="center"> +<table border="2" cellpadding="6" cellspacing="0" summary="Hazard Chart"> + <tr> + <td class="tdc">Hazard</td> + <td class="tdc">Location</td> + <td class="tdc">What I Did</td> + </tr> + <tr> + <td class="tdli">Loose prong on lamp plug</td> + <td class="tdli">Living Room</td> + <td class="tdli">Replaced with new plug</td> + </tr> + <tr> + <td class="tdli">Cracked insultor on service wire in house</td> + <td class="tdli">Back of house</td> + <td class="tdli">Notified power supplier</td> + </tr> + <tr> + <td class="tdli">Conduit not securely clamped to box</td> + <td class="tdli">Basement by fuse box</td> + <td class="tdli">Notified parents</td> + </tr> + <tr> + <td class="tdli">Extension cord, old and worn</td> + <td class="tdli">Basement, by washing machine</td> + <td class="tdli">Replaced with new rubber-covered one and protected it from water</td> + </tr> +</table></div> + +<hr class="chapter" /> + +<p><span class="pagenum">[39]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-10">LESSON NO. B-10</h2> + +<p class="h4">Credit Points 3</p> + +<h3>HOW ELECTRIC BELLS WORK—FOR YOU</h3> + +<div class="figcenter"> +<img src="images/p39_phonecall.jpg" width="300" height="163" alt="" /> +</div> + +<p>When was the last time you wanted to get +a simple message like "You're wanted +on the telephone," "There's someone here to +see you, "or "There's a car in the driveway," +to someone around your place? Did you have +to walk or run some distance and perhaps +shout, too, to be heard by the other person? +Perhaps you had to stop some other work, or +interrupt your favorite kind of fun, to do this +bit of messenger work.</p> + +<p>If the nature of the message is like one of +those mentioned, and the number of people +in hearing is not too great, then perhaps you +can use bells or buzzers or both to do some +of your messenger work for you. Even +though a bell or a buzzer can't talk, it can +convey a message.</p> + +<h3>What to Do</h3> + +<p>1. Learn how bells and buzzers work, +and learn about the many different kinds.</p> + +<p>2. Plan and install a bell system for your +home or farm.</p> + +<h3>Bells and Buzzers Can Tell a Lot</h3> + +<p>Electric bells and buzzers use the same +basic principle as the telegraph system, invented +by Samuel Morse in 1840. Although +not as important today as it was before radio, +telephone, and teletype became common, the +telegraph is still in use.</p> + +<p>Bells and buzzers, however, are very common +and have many uses. They are most +often seen in the form of doorbells, and rare +is the new home that does not have one or +more. Service stations have bell systems to +let the operator know that a car is waiting at +the gas pumps. A clock signal reminds the +homemaker when the cooking time is completed. +Children are called to and released +from school classes by means of bells and +buzzers.</p> + +<p>Also, various alarms employing bells and +buzzers warn us when it's time to get up, or +even that the place is on fire, or that a burglar +is trying to break in!</p> + +<p>Let's find out how bells and buzzers work, +what different kinds there are, the different +ways you can control them, and how you can +put them to work for you.</p> + +<p>You'll find that buzzers and bells can help +you with your 4-H projects, and with the +proper controls, can be your eyes and voice +in a dozen places at once.</p> + +<p><span class="pagenum">[40]</span></p> + +<h3>Why They Buzz or Ring—Electromagnetism</h3> + +<p>If we were to look at an electric bell with +the cover off, we'd find that it would be very +much like Figure 1.</p> + +<p>A push on the button, which is just a switch +that is normally held "open" or off by means +of a spring, sends the current from the battery +or transformer through the circuit.</p> + +<div class="figcenter"> +<img src="images/p40_fig1.jpg" width="170" height="238" alt="" /> +</div> + +<p class="caption">Figure 1</p> + +<p>You will see that the current passes first +through two small coils of wire, and each +coil has at its center a piece of soft iron +called the core. When the current is on, the +core becomes magnetized and attracts another +piece of iron called the armature with its +clapper attached.</p> + +<p>This action rings the bell, but it also breaks +the current by pulling the spring away from +the screw on its return to the power supply.</p> + +<p>With the power off, the electromagnet lets +the spring return the armature to its normal +position, contact is made again, and the +cycle starts all over again—just as long as +you continue to push on the button.</p> + +<p>Buzzers work exactly the same way, except +that they do not have a bell and depend +instead on the vibration of the armature for +a noise that's not as loud or as musical.</p> + +<p>Gongs or chimes, that strike only once +when the button is pushed, are made by connecting +the armature with the screw by means +of a flexible wire.</p> + +<h3>A Special Kind of Electricity</h3> + +<p>Most buzzers and bells work on a much +lower voltage than you normally find in the +wires in your house. Some are made to work +at 6 volts, others at 10 volts, and still others +at slightly higher voltages.</p> + +<p>You can get these low voltages by using one +or more batteries, or by using a transformer +connected to your house current. Most bells +and buzzers are now powered through transformers.</p> + +<h3>How to Control Them</h3> + +<p>The push button is the most common means +of control. You can use one button to control +several bells, or several buttons to control +one bell, or have several buttons control +several bells. Because low voltage is used, +adding extra buttons is simple, inexpensive, +and safe.</p> + +<p>Buzzers and bells can also be controlled +by: <i>clocks</i>, as in the interval timer on an +electric range or in a school class bell system; +<i>temperature detectors</i>, as in a fire +alarm or freezer alarm; <i>door and window +trips</i>, as in a one-man repair shop or in a +burglar alarm; and <i>treadles</i>, as in the driveway +of a service station.</p> + +<div class="figcenter"> +<img src="images/p40_fig2.jpg" width="237" height="217" alt="" /> +</div> + +<p class="caption">Figure 2</p> + +<p><span class="pagenum">[41]</span></p> + +<h3>Pick the Right Bell or Buzzer</h3> + +<p>Some of the many different types of bells, +and various ways of controlling them are +suggested in the table below. Just remember +that no matter what the job or conditions, +you can probably find a bell or buzzer and +controls that suit your need.</p> + +<p class="spacer"> </p> + +<div class="center"> +<table border="2" cellpadding="10" cellspacing="0" summary="buzzer jobs"> + <tr> + <th colspan="5">SOME TYPICAL JOBS FOR BELLS & BUZZERS</th> + </tr> + <tr> + <td class="tdl">Job</td> + <td class="tdl">Type of bell or buzzer</td> + <td class="tdl">Number and location of bells and buzzers</td> + <td class="tdl">Type of control</td> + <td class="tdl">Number and location of controls</td> + </tr> + <tr> + <td class="tdl">Summon others to the telephone</td> + <td class="tdl">In the house— small to medium buzzers<br /> + In outbuildings— medium to large bells<br /> + Outdoors— large weatherproof bell<br /> + All transformer-powered</td> + <td class="tdl">Enough to cover all usual work locations</td> + <td class="tdl">Push-buttons</td> + <td class="tdl">One at the telephone and each extension phone</td> + </tr> + <tr> + <td class="tdl">Notify club member that car is at his produce stand</td> + <td class="tdl">Medium to large bell— transformer-powered</td> + <td class="tdl">One may be enough—if mounted on the back of the stand</td> + <td class="tdl">Hose diaphragm<br /> + (Complete driveway units including control, are available, ready to plug in.)</td> + <td class="tdl">One—in the driveway</td> + </tr> + <tr> + <td class="tdl">Warn of power failure to incubator or brooder</td> + <td class="tdl">Battery-powered buzzer, medium size</td> + <td class="tdl">One near the poultryman's bedroom</td> + <td class="tdl">Relay, held open as long as power is on, closed by spring if interruption occurs</td> + <td class="tdl">One, at main switch of hatchery or brooder house</td> + </tr> + <tr> + <td class="tdl">Warn of dangerously warm temperature in freezer</td> + <td class="tdl">Battery-powered buzzer, medium size</td> + <td class="tdl">One, in or near the kitchen</td> + <td class="tdl">Temperature detector (sensitive thermostat)</td> + <td class="tdl">One, with bulb inside freezer</td> + </tr> +</table> +</div> + +<p class="spacer"> </p> + +<h3>How to Plan Your System</h3> + +<p>To save your time and steps when the telephone +rings for someone else in your family +who is some distance away, you can install a +simple bell or buzzer system to summon that +person.</p> + +<p>First, you must plan what you are going to +do. On a large sheet of paper, draw to scale +(roughly) a plan of your house and grounds, +including those places where phones are located. +It will help if you rule off your paper +in 1/8" or 1/4" squares and let each square +equal one foot. Show the location of poles +supporting your wiring.</p> + +<p>Next, pick out those areas where you or +others would likely be when someone else +would answer the phone and want to call you +to it.</p> + +<p>After you have thought about this, and +talked it over with members of your family, +show locations on your plan where you think +you would like to have buzzers or bells, and +show a button beside each telephone. (Generally, +you should have a bell or buzzer near +each phone, also.)</p> + +<p>Figure 3 shows diagrams of various types +of systems, and will help you determine the +number of wires you will have to install to +connect the buttons and bells that you have +planned.</p> + +<p>Inside, you will connect your transformer +and the various buttons and bells with ordinary +indoor bell wire. Outdoors, however, you +should use weatherproof 2-wire or 3-wire +telephone twist.</p> + +<p>Show on your plan the distances that must +be traversed by each type of wire, and show +the number of conductors in each. Don't +overlook the vertical distances (one floor to +another).</p> + +<p><span class="pagenum">[42]</span></p> + +<div class="figcenter"> +<img src="images/p42_fig3.jpg" width="400" height="207" alt="" /> +</div> + +<p class="caption">Figure 3</p> + +<h3>Materials You'll Need</h3> + +<p>Because no two situations are just alike, +it will be necessary for you to make your own +list of materials.</p> + +<p>As a guide, however, here is a list of +typical materials, with the quantities left +blank, for you to fill in as your own requirements +and measurements dictate.</p> + +<p class="hang"><br /> + 10-volt transformer<br /> +_____ Door buzzers<br /> +_____ Doorbells<br /> +_____ Weatherproof outdoor type bells<br /> +_____ ft. indoor bell wire<br /> +_____ ft. 2-wire weatherproof telephone twist<br /> +_____ ft. 3-wire weatherproof telephone twist<br /> +_____ lbs. staples (insulated)<br /> +_____ entrance insulators (for attaching + weatherproof to buildings and poles) +</p> + +<p>Because your transformer must be wired +into your regular house current, you should +have some help on this from an electrician +or other qualified person. Also, you should +get that person to review your plans and materials +list before you place an order.</p> + +<h3>Install According to Your Plan</h3> + +<p>With the aid of an electrician or other +qualified person, install your transformer, +and test it.</p> + +<p>You may then go ahead and complete your +signal system, checking carefully with your +plan, and making sure that your installations +are both electrically and mechanically secure.</p> + +<p>Test your system in all possible ways that +it might be used.</p> + +<h3>Demonstrations You Can Give</h3> + +<p>Build a demonstration board incorporating +a farm or home layout, with pushbuttons or +other controls and bells and buzzers appropriately +located. Show and tell how the system +would save time and energy.</p> + +<p>Show and tell how some of these work, and +their value: power-off alarm, freezer alarm, +fire alarm, driveway alarm.</p> + +<h3>For More Information</h3> + +<p>Ask your power supplier or your nearest +electrical supply house for catalogs or literature +on various types of signal systems, or +ask a dealer to show you equipment he has in +stock.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[43]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-11">LESSON NO. B-11</h2> + +<p class="h4">Credit Points 2</p> + +<h3><b>FIRST AID FOR ELECTRICAL INJURIES</b></h3> + +<div class="figcenter"> +<img src="images/p43_injury.jpg" width="300" height="158" alt="" /> +</div> + +<p>What would you do if you saw someone who +had been hurt by electricity?</p> + +<p>Did you know that you could save his life, +if you had taken the time to learn and practice +a few simple rules of electrical first aid?</p> + +<p>First aid training equips you to know what +to do and what not to do for the injured until +medical help can be obtained. While the main +benefits are for you and your family, no one +can call himself a good citizen if he fails to +help a stranger who has been hurt.</p> + +<p>The information given here is only for electrical +injuries. Perhaps what you learn will +inspire you to take a complete course in first +aid.</p> + +<h3>What to Do</h3> + +<p>Learn how to prevent electrical accidents, +and what to do if an electrical accident occurs.</p> + +<p>1. Make an electrical hazard hunt in your +home or on your farm. Point out to your +parents everything that should be repaired +or replaced for safety's sake.</p> + +<p>2. Read the first aid suggestions that follow. +Learn them.</p> + +<p>3. Get to know the six steps that are outlined +for mouth-to-mouth rescue breathing. +Practice them on your brother, sister, or +parents. Teach the entire family how to do +it.</p> + +<h3>Electricity Can Kill</h3> + +<p>In this day of hundreds of uses of electricity, +you should know about electrical +dangers. Electrocution can occur from either +low voltage (household type) or high voltage +currents. Sometimes household voltages are +more hazardous because people underestimate +the dangers involved.</p> + +<p>A fraction of an ampere passing through +your heart muscles can be fatal. Your body +offers some resistance to the flow of electricity +to ground. If you are standing on wet +ground or in water, or if your skin is damp, +this resistance is greatly reduced.</p> + +<p><span class="pagenum">[44]</span></p> + +<p>Wire cables within walls and cords on appliances +are all insulated with a shock proof +covering. Continued use, age, or damage +may expose a bare wire and create a hazard. +The point of exposure need be only a fraction +of an inch. Cords are often used and abused. +Exposed wires and signs of wear are danger +signals.</p> + +<p>Always be wary of overhead wires. People +have been injured or killed when kite strings, +model plane control lines, irrigation pipe, +and water well equipment have come in contact +with the power supplier's or their own +overhead wiring.</p> + +<h3>Prevent Accidents</h3> + +<p>Underwriters' Laboratories (UL) have +taken steps to see that minimum safety standards +are met in the manufacture of electrical +equipment. Look for the UL label when you +buy cords or appliances. Never place cords +under carpets or furniture, or drape them +over a nail. Replace or repair worn cords +without delay.</p> + +<div class="figcenter"> +<img src="images/p44_underwriters.jpg" width="112" height="112" alt="" /> +</div> + +<p>Be especially careful when operating electric +devices in the bathroom. Keep in mind +the dangers of a wet floor, grounded metal +pipes, and wet skin. Turning on an AC radio +while you are taking a bath is asking for real +trouble.</p> + +<p>There may be shorts in electric devices. +Keep your hands dry when using them, and +do not touch them along with grounded metal +objects. If you ever get a slight shock, sound +the danger signal and do something about it.</p> + +<h3>Think, Then Act</h3> + +<p>Your first thought in rescuing a victim +from an electrical accident should be your +own safety. Speed is also important, because +a few seconds or minutes may save a +life.</p> + +<p>The first question you should ask yourself +is "Can I quickly turn off the power?" This +would be easier to do in the home than outside. +In the case of a victim trapped in a +bathtub from a radio accidentally knocked into +the water, it might mean simply removing +the plug from the wall outlet. If a victim is +found grasping shorted, permanently installed +equipment and cannot let go, the main switch +might be used for quick release of the current.</p> + +<div class="figcenter"> +<img src="images/p44_inthebath.jpg" width="200" height="100" alt="" /> +</div> + +<p>Outdoors, especially with high tension +wires, your danger in rescue is much greater. +To handle the victim, touch him only with a +long dry stick, dry rope, or a long length of +dry cloth. Be sure your hands are dry and +that you are standing on a dry board. A +broom might be a good lever to pry a victim +from a high tension wire but never use a +green stick containing sap.</p> + +<div class="figcenter"> +<img src="images/p44_drystick.jpg" width="225" height="143" alt="" /> +</div> + +<p><span class="pagenum">[45]</span></p> + +<h3>First Aid</h3> + +<p>Once the rescue has been made and the +victim is free of further danger, check to +see if breathing has stopped. If so, start +artificial respiration <i>immediately</i> and send +someone for a doctor.</p> + +<p>Artificial respiration must be started as +soon as possible after normal breathing +ceases. <i>Most persons will die within 6 minutes +or less if breathing stops completely +unless they are given artificial respiration.</i> +Precious minutes may have passed before +you get to the victim. Since the victim may +be within seconds of death by the time you +are able to touch his body, you should seek +to obtain an air flow to and from the lungs +<i>immediately</i>.</p> + +<p>The victim may seem stiff as an effect of +the current, so don't give up easily. Continue +the procedure for several hours. If +transportation is necessary, remember that +there may be internal injury, fractures, or +severe burns.</p> + +<h3>Mouth-To-Mouth Rescue Breathing</h3> + +<p>There are various effective ways to give +artificial respiration, each with its advantages +and disadvantages. The mouth-to-mouth +method is recommended as a good one to +master. It can be used on victims of drowning, +suffocation, and asphyxiation, too. +People have been known to save lives with +less exposure to the correct procedure than +you are getting by reading this. So, pay attention +and remember what you read.</p> + +<p>Step 1. Turn the victim on his back. Wipe +out victim's mouth quickly. Turn his head +to the side. Use your fingers to get rid of +mucus, food, sand, and other matter.</p> + +<div class="figcenter"> +<img src="images/p45_headposition.jpg" width="162" height="127" alt="" /> +</div> + +<p class="caption">Head Position</p> + +<p>Step 2. Straighten victim's head and tilt +back so that chin points up. Push or pull his +jaw up into jutting out position to keep his +tongue from blocking air passage. This position +is essential for keeping the air passage +open throughout the procedure.</p> + +<div class="figcenter"> +<img src="images/p45_pushjawup.jpg" width="117" height="137" alt="" /> +</div> + +<p class="caption">Push Jaw Up</p> + +<div class="figcenter"> +<img src="images/p45_pinchnostrils.jpg" width="137" height="137" alt="" /> +</div> + +<p class="caption">Pinch Nostrils</p> + +<p>Step 3. Take a deep breath, place your +mouth tightly over victim's mouth, and pinch +nostrils closed to prevent air leakage. For +a baby, cover both nose and mouth tightly +with your mouth. (Breathing through handkerchief +or cloth placed over victim's mouth +or nose will not greatly affect the exchange +of air.)</p> + +<div class="figcenter"> +<img src="images/p45_breathe.jpg" width="162" height="130" alt="" /> +</div> + +<p class="caption">Breathe</p> + +<p>Step 4. Breathe into victim's mouth or +nose until you see his chest rise. (Air may +be blown through victim's teeth, even though +they may be clenched.)</p> + +<p>Step 5. Remove your mouth and listen for +the sound of returning air. If there is no +air exchange, recheck jaw and head position. +If you still do not get air exchange, turn +victim on side and slap him on back between +shoulder blades to dislodge matter that may +be in throat. Again, wipe his mouth to remove +foreign matter.</p> + +<p>Step 6. Repeat breathing, removing mouth +each time to allow air to escape. For an +adult, breathe about 12 times per minute. +For a child, take relatively shallow breaths, +about 20 per minute. Continue until victim +breathes for himself.</p> + +<p><span class="pagenum">[46]</span></p> + +<h3>What Did You Learn? True or False</h3> + +<p>1. A broken arm should be splinted before +artificial respiration is applied to a victim +who is not breathing.</p> + +<p>2. A person who has been severely shocked +with an electric current should lie down.</p> + +<p>3. A doctor should be called even though +you successfully have revived a victim's +breathing.</p> + +<p>4. A fraction of an ampere through the +human heart muscles can be fatal.</p> + +<p>5. A copper wire would provide a better +path than your body for stray currents, therefore +all appliances should be grounded if +possible.</p> + +<p>6. Outside wires are never a hazard because +they are covered with insulation when +they are installed.</p> + +<p>7. Cords need not be repaired until you +can see bare wires.</p> + +<p>8. Tuning in an AC radio while you are +bathing is always dangerous, even though +your hands are dry.</p> + +<p>9. In an emergency, a broom is an acceptable +tool for prying a victim off a high +tension wire.</p> + +<p>10. In mouth-to-mouth breathing, an +adult's lungs should be filled 12 times per +minute and a child's 20.</p> + +<h3>Demonstrations You Can Give</h3> + +<p>Show how to deal with an electrical first +aid "problem" given to you by your leader.</p> + +<h3>For More Information</h3> + +<p>Ask your leader to have a first aid expert +put on a demonstration. (Many industrial +plants and power suppliers have such people.)</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[47]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-12">LESSON NO. B-12</h2> + +<p class="h4">Credit Points 3</p> + +<h3><b>HOW ELECTRICITY HEATS</b></h3> + +<div class="figcenter"> +<img src="images/p47_popcorn.jpg" width="300" height="168" alt="" /> +</div> + +<p>In ancient times, people thought that heat +was a material just as air is. They +called it "caloric". When something got +warm, they said, caloric flowed into it. +When something cooled off, caloric flowed +out of it. It did not bother them that they +could not see caloric. They could not see +air either!</p> + +<p>Now we know that heat is not a material. +It does not take up space. It does not weigh +anything. Instead, it is a form of energy. +And when we say that heat is a form of energy, +we mean that it can be used to do work.</p> + +<h3>What to Do</h3> + +<p>1. Make a simple resistance heater.</p> + +<p>2. Make some popcorn by:</p> + +<p>(a) conduction (b) convection +(c) radiation</p> + +<h3>"Resistance" Makes Heat</h3> + +<p>There are at least four ways that electricity +can make heat. The one that we'll +cover here is <i>resistance</i> heating. (The others +are: <i>dielectric</i> heating, where the lines of +force of an electrostatic field pass through a +non-conductive material and heat it; the <i>heat +pump</i>, which is a refrigerator in reverse; +and <i>electronic</i> heating, which uses high frequency +waves similar to radio waves to create +high speed movement of the molecules or tiny +particles which rub together to make heat.)</p> + +<p><i>Resistance</i> heating occurs because every +conductor of electricity opposes the flow of +current through it. Some conductors resist +more than others. When they do, a certain +amount of warming takes place. The more +resistance that is offered, the more heating +there is.</p> + +<p>Some materials, like silver, copper, and +aluminum, offer little resistance. We say +they are good conductors.</p> + +<p>Other materials, like iron, offer more +resistance. They are still conductors, but +not as good as the others mentioned.</p> + +<p><span class="pagenum">[48]</span></p> + +<p>The <i>size</i> of the conductor, and its <i>length</i> +are the other two things that affect its resistance. +The <i>smaller</i> it is, the greater its +resistance. Also, the <i>longer</i> it is, the +greater its resistance. Therefore, when we +only want to <i>move</i> electricity from place to +place, we want relatively large, "good" conductors. +Here, we do not want to make heat. +In fact, we want to avoid it, because too +much heat in the wrong place can cause a +fire.</p> + +<div class="figcenter"> +<img src="images/p48_filament.jpg" width="150" height="118" alt="" /> +</div> + +<p>But when we want heat, we choose relatively +small, "poor" conductors, and the +more heat we want, the longer they must be. +If you will think of the filament inside a lamp +bulb; you may recall that it is a very fine +wire, coiled so as to get a maximum length, +and made of tungsten which has a high resistance.</p> + +<p>Because of all these factors, this filament +glows at a white heat, and is a source of +both light and heat.</p> + +<h3>Make a Simple Resistance Heater</h3> + +<p class="hang"><i>Materials you will need</i>:<br /> +1 dry cell battery<br /> +1 foot iron picture wire<br /> +Pliers</p> + +<p>Use a short strand of iron picture wire +and hook the ends to the terminals of a dry +cell battery. Use pliers so that you do not +burn your fingers. Disconnect the wires as +soon as they become hot. Tell why the wires +heat.</p> + +<div class="figcenter"> +<img src="images/p48_resistance.jpg" width="175" height="100" alt="" /> +</div> + +<h3>Conduction is "Touching" Heat</h3> + +<div class="figcenter"> +<img src="images/p48_fryingpan.jpg" width="185" height="95" alt="" /> +</div> + +<p>Conduction occurs when you set a pan containing +food right on a heating element. An +egg cooking in a hot frying pan is a good example +of conduction at work. This method +is the most efficient single way of using electric +heat for cooking.</p> + +<h3>Convection Depends on Air</h3> + +<div class="figcenter"> +<img src="images/p48_oven.jpg" width="182" height="187" alt="" /> +</div> + +<p>Convection warms food in pans that are +not actually touching the heating element. It +uses the hot air around the element to carry +heat to the pan.</p> + +<p>Your oven in your range works by convection. +Most houses are warmed in winter in +the same way. The heat produced in a furnace +warms the air as it circulates through. +This air in turn keeps your body warm.</p> + +<p><span class="pagenum">[49]</span></p> + +<h3>Radiation is Like the Sun</h3> + +<p>Radiation heating is more difficult to explain. +It results when heat or energy waves +strike an object and are converted into heat. +The energy we receive from the sun is a good +example. When you are wearing dark clothes +on a chilly day, you may become uncomfortably +hot. The sunshine warms you even +though the air around you has not been heated. +Radiant energy has a way of being absorbed +by dark objects and reflected by light colored +or shiny surfaces. Did you ever notice how +snow melts faster on a black top road than it +does on a concrete road?</p> + +<div class="figcenter"> +<img src="images/p49_snowmelt.jpg" width="182" height="169" alt="" /> +</div> + +<p>The electric heat lamp is one of the most +familiar sources of radiant heat. Other examples +are panels and cables that are built +into the walls and ceilings of homes to provide +heat.</p> + +<h3>Make Popcorn 3 Ways</h3> + +<p>How do you make popcorn? Did you know +that you can do this kind of a heating job three +different ways?</p> + +<p class="hang"><i>Materials Needed</i><br /> +Popcorn<br /> +Cooking oil or shortening<br /> +Salt and butter<br /> +4-qt. saucepan, with cover. (A glass cover is preferred.)<br /> +Potholder<br /> +Electric range<br /> +2 250-watt heatlamps<br /> +2 spring clamp type lampholders<br /> +Wire mesh corn popping basket or wire mesh kitchen strainer (improvise a screen wire cover)</p> + +<p><i>First</i>, make popcorn the way you usually +do. Set a front surface unit control on the +range at "medium high". Pour enough oil to +very lightly cover the bottom of the pan. +When the pan is hot, pour in enough popcorn +to cover the bottom with one layer of kernels. +Use the potholder in one hand to hold the +cover on, and with the other move the pan +back and forth across the unit. When the +popping stops, remove from the heat.</p> + +<p>How did the heat get to the popcorn?</p> + +<p><i>Second</i>, make popcorn in the oven. Add +the oil to the pan, cover it and put it in the +oven. Turn the oven on, with the automatic +control set at 400°. When the oven indicator +light goes off, this means that the proper +temperature has been reached. With the +potholder, remove the pan and add one layer +of popcorn kernels. Replace the pan in the +oven. When the popping stops (listen for it) +remove the pan.</p> + +<p>What kind of heating took place here?</p> + +<p><i>Third</i>, make popcorn with the heat lamps. +Clamp the lampholders to the back of a chair +or other vertical support. They should be 6 +to 8 inches apart and pointed directly at each +other. Put about 2 tablespoonfuls of popcorn +in the Wire basket or strainer. Do not add +oil. Hold the basket midway between the two +lamps. When the popping stops, turn off the +lamps.</p> + +<p>What kind of heating was this?</p> + +<p>Now, butter and salt the popcorn you have +made and share it with others.</p> + +<h3>What Did You Learn?</h3> + +<p>1. How is heat transferred from one body +to another?</p> + +<p>2. Could chicks or pigs receive warmth +from a heat lamp without the air in the pens +becoming warm? Explain.</p> + +<p>3. How does a broiler unit in a range cook +meat?</p> + +<p>4. How does an oven bake food?</p> + +<p>5. Tell why iron picture wire was used +instead of copper wire for your heating demonstration.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[50]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-13">LESSON NO. B-13</h2> + +<p class="h4">Credit Points 2</p> + +<h3><b>MYSTERIOUS MAGNETISM</b></h3> + +<div class="figcenter"> +<img src="images/p50_magnetism.jpg" width="182" height="245" alt="" /> +</div> + +<p>In ancient times, people found certain +rocks that clung together in bunches. +These rocks were very mysterious. People +didn't understand them and many superstitions +grew up about lodestones, as these rocks +were called. Lodestone (sometimes spelled +loadstone) means leading stone. People even +told Columbus not to sail out of sight of land +because a giant lodestone was just over the +horizon waiting to pull all the nails out of his +ships.</p> + +<p>The Chinese were the first to use magnets. +They found that if you hung a lodestone by a +string, one end of the stone would always +point in the direction of the North Star. They +had the first magnetic compasses.</p> + +<p>An artificial magnet can be made by stroking +or gently rubbing a piece of steel with a +lodestone. This piece of steel then can be +used to magnetize another piece of steel. +This can be continued on and on. Lodestones +are not always available but you can get the +same results with an electric current. So, +magnetism and electricity are very closely +related.</p> + +<h3>What to Do</h3> + +<p>Learn about magnetism by doing the experiments +that follow.</p> + +<p>Seeing is believing!</p> + +<p class="hang">Materials You Will Need<br /> +2 dry cell batteries (#905)<br /> +A few feet of No. 18 bell wire<br /> +3 steel knitting needles or similar hard steel<br /> +2 ft. of light thread<br /> +Sheet of light cardboard or stiff paper<br /> +Permanent magnet (bar or horseshoe)<br /> +Compass<br /> +1 or more large nails or spikes<br /> +Red and black china-marking pencils or crayons<br /> +<br /> +Iron filings<br /> +Wire cutters<br /> +Carpet tacks</p> + +<p>(Iron filings usually can be found under the +grinding wheel in a shop. If you can't find +any, rub some steel wool pads together to +produce bits of metal that will do.)</p> + +<h3>"See" a Magnetic Field</h3> + +<p>Cover the permanent magnet with the cardboard +or paper. Sprinkle iron filings on the +paper. Tap the paper and note the pattern +formed. Strings or lines of filings pass from +one pole of the magnet to the other. The +area covered by the filings is the center of +the magnetic field. To remember this, you +might compare the magnetic lines of force +that arrange the iron filings to the contour +strips in a farmer's field.</p> + +<p>This magnetic field is one of the important +things in our everyday life with electricity. +If it were not for the magnetic field, we would +not have electric motors. Telephones, +radios, television, and many other things we +use every day also depend on this magnetic +field.</p> + +<p><span class="pagenum">[51]</span></p> + +<div class="figcenter"> +<img src="images/p51_fig1.jpg" width="182" height="136" alt="" /> +</div> + +<p class="caption">Figure 1</p> + +<h3>Make an Electro-Magnet</h3> + +<p>You can make magnetism work for you by +winding several turns of insulated wire around +one or more large nails or spikes (soft iron). +Connect one end of the wire to the battery. +Touch the other end of the wire to the other +terminal for a few seconds and see how many +tacks you can pick up. Repeat the experiment +using as many turns as possible. How +many more tacks were you able to pick up?</p> + +<div class="figcenter"> +<img src="images/p51_fig2.jpg" width="182" height="138" alt="" /> +</div> + +<p class="caption">Figure 2</p> + +<p>You have made what we call an electromagnet. +When you disconnect the wire, the +nails fall off. This is one of the advantages +of an electromagnet. We can turn magnetism +on and off as we wish. Picture a crane operator +throwing the switch and picking up scrap +iron and steel. Then he opens the switch to +drop the scrap metals.</p> + +<p>Soft iron can be magnetized easily as you +have just seen, but loses its magnetism in a +short time. Steel is harder to magnetize but +holds its magnetism almost indefinitely.</p> + +<h3>Make a Permanent Magnet</h3> + +<p>Wrap the insulated bell wire around the +steel knitting needle. The wire should be +wrapped the full length of the needle. One +end of the wire is connected to the battery. +The other end of the wire is then touched for +just a few seconds to the other terminal. This +should make the needle into a permanent bar +magnet. If you did not get results, try two +batteries in series, wind more turns of wire +on the needle, and leave it connected a little +longer. Do the same thing with the second +knitting needle. In the same way, you can +magnetize a screwdriver, so that you can use +it to pick up and hold steel screws. Don't +do it unless you want your screwdriver to be +magnetized.</p> + +<div class="figcenter"> +<img src="images/p51_fig3.jpg" width="182" height="153" alt="" /> +</div> + +<p class="caption">Figure 3</p> + +<h3>See How They Attract and Repel</h3> + +<p>Take one of the magnetized needles and +hang it with a thread. A thread stirrup +(Figure 4) will help keep it level. Be sure +it is not near other large pieces of steel. +Watch the needle. Does it settle down, pointing +in one direction? (Check to see if this +is the same direction as your compass). If +it does, you have made a compass. The tip +of the needle pointing north is called the +North Pole (North-seeking pole). The other +end is called the South Pole. Mark the North +Pole with a stroke of the red marking pencil. +Mark the South Pole black. Do the same +thing with the second needle. You can show +this with a sewing needle, and a notched +cork, and a bowl of water. Rest the needle +in the notched cork, and float it on the water.</p> + +<p><span class="pagenum">[52]</span></p> + +<div class="figcenter"> +<img src="images/p52_fig4.jpg" width="182" height="126" alt="" /> +</div> + +<p class="caption">Figure 4</p> + +<p>Hold the compass near the North Pole of +the needle. What happens? Does the South +Pole of the needle attract the North or South +Pole of the compass? Try this with the second +magnetized needle. See if you can prove +the rule that like poles repel (drive away) +and unlike poles attract.</p> + +<div class="figcenter"> +<img src="images/p52_fig5.jpg" width="182" height="66" alt="" /> +</div> + +<p class="caption">Figure 5</p> + +<p>Connect one end of a wire loop to the battery +and run the wire directly over the compass. +Touch the other end of the wire to the +battery. Which way does the compass point +now? If you get some motion out of the compass +needle, this proves there is a magnetic +field around the wire when current is flowing. +This relation between electricity and magnetism +is the thing that makes electric motors +and generators work.</p> + +<div class="figcenter"> +<img src="images/p52_fig6.jpg" width="182" height="163" alt="" /> +</div> + +<p class="caption">Figure 6</p> + +<h3>Make Many From One</h3> + +<p>Lay the third needle (unmagnetized) on a +table and stroke it with one of the magnetized +needles. (See diagram) Always stroke it in +the same direction. Raise the magnetized +needle at least two inches on each return +stroke. Thus you can magnetize the needle +by using the other needle.</p> + +<div class="figcenter"> +<img src="images/p52_fig7.jpg" width="237" height="220" alt="" /> +</div> + +<p class="caption">Figure 7</p> + +<p>Use the wire cutters to cut the first magnetized +needle in short lengths. (Cover the +needle with a cloth to keep the pieces from +flying.) Can you show by using the compass +that each piece is a complete magnet? Hold +one end, then the other, of each piece to a +compass. Does each piece have both a North +Pole and a South Pole?</p> + +<div class="figcenter"> +<img src="images/p52_shortlengths.jpg" width="187" height="50" alt="" /> +</div> + +<h3>Magnetism and Animals</h3> + +<p>The things you have done show that electricity +and magnetism are related in many +ways. Magnetism is mysterious, and there +are still things to discover about it. It is +thought that animals and birds are aided in +their sense of direction by magnetism. It is +commonly known that when a person gets lost +in the woods, he tends to go around in circles. +Possibly this is caused by the earth's magnetic +field.</p> + +<p><span class="pagenum">[53]</span></p> + +<h3>What Did You Learn?</h3> + +<p>1. Where are natural magnets obtained?</p> + +<p>2. How can artificial magnets be made?</p> + +<p>3. What material is needed for a permanent magnet? For a temporary magnet?</p> + +<p>4. How can you find out which is the North Pole of an unmarked magnet?</p> + +<p>5. How many poles does a magnet have?</p> + +<p>6. Which magnetic poles attract each other?</p> + +<p>7. Why couldn't you make a compass out of a strip of plastic?</p> + +<p>8. What causes the compass to change direction +when a wire carrying battery current +is held over the needle?</p> + +<p>9. List the materials you would need and +tell how you would build a homemade compass.</p> + +<p>10. Tell what you enjoyed most about becoming +acquainted with mysterious magnetism.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[54]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-14">LESSON NO. B-14</h2> + +<p class="h4">Credit Points 2</p> + +<h3><b>Give your appliances and lights a square meal</b></h3> + +<div class="figcenter"> +<img src="images/p54_starvation.jpg" width="400" height="263" alt="" /> +</div> + +<p>Would you say that having enough to eat +was pretty important in the home that +you know?</p> + +<p>The "food" for your appliances and lights +is electricity, and like you they must be +"fed" enough.</p> + +<h3>What to Do</h3> + +<p>1. List the appliances and lights in your +home.</p> + +<p>2. See if any of them are "starving" for +the electricity they need.</p> + +<p>3. Learn how the electricity gets to where +it's used.</p> + +<p>4. Make a chart of the electrical circuits +in your home.</p> + +<p>5. Make sure that each circuit is protected +with the right fuse or circuit breaker.</p> + +<h3>Count Your Electrical Blessings</h3> + +<p>Many people in much of the rest of the +world wish that they could trade places with +us, because we have so many electrical appliances +in our homes.</p> + +<p>Of course, we have not always had as +many appliances as there are today. When +electricity first came along, people used it +only for lights. Then, they began to add +flatirons, washing machines, refrigerators, +coffee percolators, and radios.</p> + +<p>Then more and more electrical things +were made for people to use and enjoy. Now +we have dozens and dozens of uses for electricity +in our homes.</p> + +<p><span class="pagenum">[55]</span></p> + +<p>How many different uses for electricity +are there in your home today? Ask your +parents how many there were when your +home was built or first wired. How many +were <i>common</i> when your parents began to +keep house?</p> + +<h3>Some Homes Are Behind Times</h3> + +<p>Many older homes were built before electricity +was available, and were wired later. +And like them, some older homes that +were wired as they were built had only enough +wiring for lights and a few other appliances, +because those were the only uses that were +known at that time.</p> + +<div class="figcenter"> +<img src="images/p55_rocking.jpg" width="182" height="104" alt="" /> +</div> + +<p>But people kept on living in these homes, +and kept adding to the uses they made of +electricity without adding to their wiring.</p> + +<p>What has this meant? Well, if electricity +were like cars and trucks, you could say +that some people are trying to put turnpike +traffic through a back-country dirt road!</p> + +<h3>Watch for Signs of Starvation</h3> + +<p>Of course, as your state has done with its +highways, some people have expanded and +modernized their wiring. But many others +have not yet seen this need, or if they have, +they may have to do it again.</p> + +<p>Here's why:</p> + +<p>Your power supplier delivers current to +you at the right voltage or electrical pressure. +If the wires in your house are large +enough, they will pass this full voltage on to +the appliances.</p> + +<p>But if your wiring is too small, the electricity +arrives at the appliances so weak +that they can't work properly, and much of +what you pay for is wasted.</p> + +<p>Here are some things you can watch for +in your own home. They will tell you whether +your appliances are getting enough electrical +"food" or not.</p> + +<p>1. <i>A shrinking TV picture</i>—If it draws +in from the sides of the screen, fades, loses +contrast, or if the sound becomes distorted, +you may have low voltage.</p> + +<p>2. <i>Too much fuse blowing or circuit +breaker tripping.</i></p> + +<p>3. <i>Heating appliances are slow to do their +jobs.</i></p> + +<p>4. <i>Lights dimming</i>, when motors or other +appliances are turned on.</p> + +<p><b>There Should Be Enough Ways +to Get "Appliance-Food" Around</b></p> + +<p>If appliances in your home show these +starvation signs, then you may not have +enough ways for the electricity to get to +where it's used.</p> + +<p>There are three kinds of these electrical +highways or circuits, and your home should +have enough of each:</p> + +<p>1. <i>General purpose circuits</i>—These +serve lights all over the house, and convenience +outlets everywhere except in the +kitchen, laundry, and dining areas.</p> + +<p>A rule-of-thumb is: There should be at +least one general purpose circuit for each +500 sq. ft. of floor space.</p> + +<p>2. <i>Small appliance circuits</i>—These are +not used for lights, but instead they supply +convenience outlets in the kitchen, laundry, +and dining areas where portable appliances +are most used.</p> + +<p>Every home should have at least two +small-appliance circuits.</p> + +<p>3. <i>Individual or special-purpose circuits</i>—One +of these is needed for each: electric +range, dishwasher, water heater, freezer, +automatic washer, clothes dryer, air conditioner, +pump, and house heating equipment.</p> + +<p><span class="pagenum">[56]</span></p> + +<div class="figcenter"> +<img src="images/p56_wiresize.jpg" width="250" height="255" alt="" /> +</div> + +<p class="caption">Wire sizes commonly used in homes</p> + +<h3>Each Circuit Big Enough</h3> + +<p>The capacity of each circuit is limited by +the size of its wires. The chart above shows +you the actual sizes of wires commonly used +in permanent home wiring, and what each +will carry. Notice that each size is given a +number, and the smaller the number, the +bigger the wire.</p> + +<p>Also notice that a given size of wire will +carry twice as many watts at 230 volts as it +will at 115 volts. (Watts are figured by +multiplying amps times volts.)</p> + +<p>General purpose circuits usually are +either Number 14 or Number 12 wire, at +115 volts. What is the capacity of each, in +watts? (Number 12 wire is recommended +for all new general purpose circuits.)</p> + +<p>Small appliance circuits are required to +be at least Number 12 wire.</p> + +<p>Individual circuits are always sized according +to the appliance they serve. Find +the size wire that should be used for a +10, 000-watt, 230-volt range; a 1500-watt, +115-volt dishwasher; a 4500-watt, 230-volt +clothes dryer. ________ ________ ________</p> + +<h3>Only One Fuse Size Right</h3> + +<p>A fuse in an electrical circuit is like an +alert traffic policeman—stopping everything +if there's danger. A circuit breaker serves +the same purpose, and the right size is installed +when the wiring is done.</p> + +<p>A policeman uses his brain to tell him +when to blow his whistle, but a fuse depends +on the size of the little fusible (meltable) +metal link that you see under the glass.</p> + +<p>If too great an electrical load is added to +a circuit, this link will melt and prevent a +dangerous overload. If you put in a fuse +with too heavy a link, it will not melt in +time, and the wiring and equipment may be +damaged.</p> + +<p>Therefore the right size of fuse is very +important, and is something that you should +check in your own home.</p> + +<p>See the chart above for the right fuse for +each size wire.</p> + +<h3>Make a Circuit Chart</h3> + +<p>At one or more places in your home there +is a box or panel containing the fuses or +breakers for the various circuits. Attached +to the inside of the door of each such panel +should be a chart something like this:</p> + +<div class="figcenter"> +<img src="images/p56_fusesize.jpg" width="212" height="182" alt="" /> +</div> + +<p>Notice that in our chart we have made +columns for a description of what each circuit +serves, its number or position in the +panel, and the proper size fuse for it.</p> + +<p>Because most such charts leave out this +last very important bit of information, you +should make a complete new chart, like the +one shown. Provide as many lines as there +are fuse positions. Paste or tape it to the +inside of the panel door.</p> + +<p><span class="pagenum">[57]</span></p> + +<p>Then, ask permission of your parents to +disconnect all the circuits by unscrewing the +fuses or flipping the circuit breakers. <i>Do +not touch anything but the fuse rim.</i> Then +reconnect them, one at a time, to find out +what each circuit serves. Turn on as many +lights as you can, to help you in your detective +work. Use a test lamp at those outlets +that do not have a light connected to +them. Write two or three words describing +each circuit on the proper line on your chart.</p> + +<p>On a separate sheet, keep track of the +appliances and lights that are on each circuit, +and add up the watts. (If the name-plate +of any appliance gives "amperes", +"amps", or "A" instead of watts, just remember +that amps times volts equals watts.) +This will tell you if any of them are overloaded. +Show this sheet to your parents.</p> + +<h3>Check the Wire Sizes</h3> + +<p><i>Disconnect the main switch</i>, and determine +the size of the wires in each circuit. +Don't include the insulation in your measurement.</p> + +<blockquote><h4><i>BE CAREFUL!</i></h4> +<p><b><i>Even though you have disconnected +the main switch, the wires coming +into it are still "live". So, do not touch +any wires. Instead hold the wire size +chart near them so that you can tell +which gauge each one is.</i></b></p></blockquote> + +<p>Write in the proper size fuse for each +circuit on your chart.</p> + +<h3>Replace Any Wrong-Size Fuses</h3> + +<p>Do the fuse sizes you have written on your +chart agree with the ones that are in place +in the panel?</p> + +<p>Get the right size fuses and replace any +that are wrong. Make sure that you have a +reserve supply of the right sizes, and that +they are handy for future use.</p> + +<h3>Talk it Over With Your Parents</h3> + +<p>Do you think that your home has enough +of the proper size circuits? If not, talk it +over with your parents. They may want to +ask an electrician to go over the wiring and +make the necessary changes.</p> + +<h3>What Did You Learn?</h3> + +<p>(Underline the right answer.)</p> + +<p>1. A (television set, radio) is very sensitive +to changes in voltage.</p> + +<p>2. Dimming lights mean (static in the +wires, an electrical overload).</p> + +<p>3. Wires that become warm from overload +make it (more expensive, cheaper) to +operate the equipment.</p> + +<p>4. A home of 2,000 sq. ft. should have +at least (three, four) general purpose circuits.</p> + +<p>5. One solution to low voltage symptoms +is (heavier fuses, more circuits).</p> + +<p>6. Full capacity for a Number 14 wire +circuit at 115 volts is (1725 watts, 3000 +watts).</p> + +<p>7. A room air conditioner should be on +(a general purpose, an individual) circuit.</p> + +<p>8. The purpose of a fuse is to (let you +disconnect the circuit, automatically prevent +overloading the circuit).</p> + +<p>9. The right size fuse is determined by +(wire size, the store where you buy it).</p> + +<p>10. A circuit chart should give (circuit +description and fuse size, the maker's +name).</p> + +<h3>Demonstrations You Can Give</h3> + +<p>Ask your leader to help you plan a demonstration. +You can show how lights dim +when too many other appliances are connected, +how a fuse protects against overloading, +and the danger of using too large a +fuse.</p> + +<h3>For More Information</h3> + +<p>Ask your Extension agent, power supplier, +or electrician for additional help.</p> + +<hr class="chapter" /> + +<p><span class="pagenum">[58]</span></p> + +<div> +<img src="images/electprog_logo.jpg" width="50" height="70" alt="" class="split" /> +<img src="images/4h_logo.jpg" width="60" height="60" alt="" class="splitr" /> +</div> + +<h2 id="LESSON_NO_B-15">LESSON NO. B-15</h2> + +<p class="h4">Credit Points 4</p> + +<h3><b>YOU CAN MEASURE ELECTRICITY</b></h3> + +<div class="figcenter"> +<img src="images/p58_measure.jpg" width="300" height="163" alt="" /> +</div> + +<p>Instruments that can detect or measure +the flow of electricity have helped to +make possible the wonders of electricity as +we know them today.</p> + +<p>Scientists in laboratories must have measuring +devices for experiments leading to +new uses of electricity. Power suppliers +must have instruments that tell what the generating +equipment is doing and to measure +the amount of electricity being sold to users. +Factories need instruments that keep tab on +electrical equipment to make sure electricity +is being used efficiently.</p> + +<p>In fact, almost anywhere you find electric +power at work you'll find electrical instruments—even +in your home. The one you +know best measures the amount of electricity +used. Another, in the family car, shows +whether the generator is charging the battery +or if the battery is discharging.</p> + +<h3>What to Do</h3> + +<p>1. Make a simple kind of direct-current +meter that will show you that there's a magnetic +field around a wire carrying an electric +current and that will detect a very tiny +current.</p> + +<p>2. Make a more refined D.C. instrument +(galvanoscope) and measure the voltage of +different sizes of dry batteries, and show +how an electric current can be induced.</p> + +<p class="hang">Tools and Materials You'll Need:<br /> +Pair of pliers, knife, small hammer<br /> +30 feet of No. 24 bell or magnet wire<br /> +Compass<br /> +Two coins—a penny and a dime<br /> +Fine sandpaper<br /> +Blotting paper<br /> +Plastic or cellophane tape<br /> +Wooden blocks (See Figure 4)<br /> +Glue<br /> +2 small nails<br /> +One #905 dry cell, a penlight battery, and two regular flashlight batteries<br /> +Table salt<br /> +Drinking glass<br /> +2 paper clips<br /> +Two machine bolts +<span class="pagenum">[59]</span></p> + +<h3>How They Work</h3> + +<p>Like many electrical things, most electrical +instruments depend on the action of +magnetism created by an electric current. +There is a magnetic <i>field</i> or lines of force +around any wire carrying an electric current. +If this field is controlled and made to +react on a sensitive device, like an easily +moved pointer, we have an electrical instrument.</p> + +<h3>Detect a Magnetic Field</h3> + +<p>First, let's prove that there is a magnetic +field around any wire carrying an electric +current. Take a piece of wire about +two feet long and scrape off about an inch of +insulation from each end. Connect one end +to a battery terminal. Make a loop of wire +that crosses the face of your compass, north +to south. Now touch the other end of the +wire to the other battery terminal.</p> + +<p>(DO NOT attempt to substitute +alternating current, as from a model railroad +transformer because its alternating +current will cause the compass needle to +swing rapidly from one side to the other.)</p> + +<div class="figcenter"> +<img src="images/p59_fig1.jpg" width="182" height="109" alt="" /> +</div> + +<p class="caption">Figure 1.</p> + +<p>Put your right hand beneath the wire so +that your fingers point the way the needle deflects, +and your thumb will point in the direction that the +current is flowing.]</p> + +<p>What happens? Your compass needle +should move to one side because it is very +sensitive to magnetic influences. This +proved that the wire created a magnetic +field or lines of force when we passed electricity +through it. (Figure 1)</p> + +<h3>Detect a Tiny Current</h3> + +<p>How sensitive is your simple electric +meter? Take about five feet of wire and +wrap it around your compass as in Figure 2, +keeping the turns bunched together as much +as you can. Leave about six inches at both +ends of the wire extended for leads. Scrape +the insulation off the last inch of both. Rotate +the coil and compass until the needle +and coil are parallel, both pointing north +and south.</p> + +<div class="figcenter"> +<img src="images/p59_fig2.jpg" width="175" height="70" alt="" /> +</div> + +<p class="caption">Figure 2</p> + +<p>Take a copper penny and a dime, and +clean off any corrosion or film on the coin +faces with a bit of fine sandpaper. Now take +a piece of blotting paper about the size of +the penny and dip it into strong salt water. +Place the damp blotting paper between the +penny and the dime. Place one of your compass +coil leads against the dime, and the +other against the penny as shown in Figure +3. Be sure you have good metal-to-metal +contact between the wires and the coins.</p> + +<div class="figcenter"> +<img src="images/p59_fig3.jpg" width="125" height="125" alt="" /> +</div> + +<p class="caption">Figure 3</p> + +<p>At the instant that you squeeze the leads +against the coins, watch what is happening +to the compass needle. It should move for +an instant from the north position each time +you press the leads against the two coins.</p> + +<p>Obviously, the little coin battery you have +just made produces a very weak electrical +current. Even so, your instrument should +be able to detect it.</p> + +<h3>Make a Simple Galvanoscope</h3> + +<p>Now let's make a meter that is a little +more practical to use. Broadly speaking, a +galvanoscope is an instrument that detects +the presence of electric currents. It sounds +complicated but it is really quite simple. It +is named in honor of an Italian professor +named Galvani who made important early +experiments with electricity.</p> + +<p><span class="pagenum">[60]</span></p> + +<p>A refinement of the galvanoscope is today's +galvanometer. Other related instruments +are the voltmeter and ammeter. These +are very important instruments to the electrical +engineer.</p> + +<p>Using a glass or anything three to four +inches in diameter, wind about 20 turns of +wire in a "bunched" coil as in Figure 4. +Wrap the coil at several points with cellophane +or plastic tape to keep it from unwinding.</p> + +<div class="figcenter"> +<img src="images/p60_fig4.jpg" width="175" height="210" alt="" /> +</div> + +<p class="caption">Figure 4</p> + +<p>Make a wood base for your coil as shown +in Figure 4. The compass support blocks +can be thin wood slats. Do not attach them +with steel nails or tacks. Use glue instead. +Hold the coil in the slot between the blocks +with glue or melted wax or use copper +staples. Place the compass on the supports +and rotate the base so that the compass +needle and coil are parallel, pointing north +and south.</p> + +<h3>Measure the Voltage of Batteries</h3> + +<p>Do you know what difference the size of +dry cell battery makes in the voltage it supplies? +Your meter can tell you.</p> + +<p>To test the voltage of batteries we must +be able to control our galvanoscope. To do +this, connect a glass of strong salt water in +series with the battery as shown in Figure +5. Make sure the wire ends immersed in +the salt water are scraped free of enamel.</p> + +<div class="figcenter"> +<img src="images/p60_fig5.jpg" width="200" height="138" alt="" /> +</div> + +<p class="caption">Figure 5</p> + +<p>With one of the batteries connected, move +the wires in the salt water first closer, then +farther apart (keeping them parallel to each +other) while watching your compass needle. +When the needle stays 15 to 20 degrees off +north, lock the wires in the salt solution in +place with paper clips.</p> + +<p>Now disconnect the battery you have been +using and connect a smaller battery. If both +batteries are fresh, the compass needle +should return to almost the same spot. This +proves that both batteries regardless of size +put out the very same voltage. The larger +ones, however, are designed to last longer.</p> + +<p><b>Measure the Difference +between Series and Parallel</b></p> + +<p>Using the salt solution as in the previous +experiment, connect two flashlight batteries +in series as shown in Figure 6. The compass +needle should move about twice as far +as it did with one battery connected. This +shows that when you connect batteries this +way you double their voltage.</p> + +<div class="figcenter"> +<img src="images/p60_fig6.jpg" width="200" height="133" alt="" /> +</div> + +<p class="caption">Figure 6</p> + +<p><span class="pagenum">[61]</span></p> + +<p>Now place your batteries side by side and +connect the two top terminals and the two +bases as shown in Figure 7. The compass +needle should move only as much as it did +for one battery. This is called a parallel +connection. You can see that this arrangement +does not double the voltage, even +though you used two batteries.</p> + +<div class="figcenter"> +<img src="images/p61_fig7.jpg" width="200" height="130" alt="" /> +</div> + +<p class="caption">Figure 7</p> + +<p>While you have this hookup, try reversing +the position of the leads connected to your +batteries. Notice that reversing the direction +of current flow in the coil causes the +compass needle to swing in the opposite direction.</p> + +<h3>Test for Induced Current</h3> + +<p>Make a simple coil by winding about 50 +turns of wire around a machine bolt core. +The bolt should be 1/4 to 1/2" in diameter +and about two inches long. Connect the coil +to your galvanoscope as shown in Figure 8. +Pass the coil back and forth close to the end +of a permanent magnet.</p> + +<div class="figcenter"> +<img src="images/p61_fig8.jpg" width="200" height="133" alt="" /> +</div> + +<p class="caption">Figure 8</p> + +<p>Notice a slight deflection of the compass +needle with each pass. You have shown that +electricity can be induced in a wire coil by +moving it through a magnetic field. Currents +generated in this way are called induced currents.</p> + +<div class="figcenter"> +<img src="images/p61_fig9.jpg" width="200" height="133" alt="" /> +</div> + +<p class="caption">Figure 9</p> + +<p>Now make another coil and core just like +the first one and arrange them and a connection +as shown in Figure 9. If you make +and break the current to the second coil, +you will build up and collapse a magnetic +field around the first coil and again induce +a current in it. You will see the compass +needle swing back and forth again.</p> + +<p>These last two experiments give you a +crude idea of how an electric generator +works, producing electric current by induction +as a coil-wound rotor revolves within +a magnetic field.</p> + +<h3>What Did You Learn?</h3> + +<p>What does every current-carrying wire +have around it? How does this help us to +measure electricity? How sensitive are +electrical instruments? What is the difference +in voltage between (a) a large and a +small dry cell? (b) batteries connected in +series and in parallel? (c) your original +connection and the reverse of it? What +similarity does the test for induced current +show between movement through a magnetic +field and the making and breaking of a direct +current?</p> + +<h3>Demonstrations You Can Give</h3> + +<p>Show others how your galvanoscope can +detect: whether a battery is producing current, +which way the current is flowing, and +whether a current is strong or weak. Demonstrate +how a current can be generated +using magnetism.</p> + +<h3>For More Information</h3> + +<p>Ask your power supplier representative +to show you some of the instruments used +by his organization, and to give you a brief +explanation of how they work. Ask him or +an electrician to give you a demonstration +of a split-core ammeter.</p> + +<p> </p> +<p> </p> +<hr class="full" /> +<p>***END OF THE PROJECT GUTENBERG EBOOK ELECTRICITY FOR THE 4-H SCIENTIST***</p> +<p>******* This file should be named 38036-h.txt or 38036-h.zip *******</p> +<p>This and all associated files of various formats will be found in:<br /> +<a href="http://www.gutenberg.org/dirs/3/8/0/3/38036">http://www.gutenberg.org/3/8/0/3/38036</a></p> +<p>Updated editions will replace the previous one--the old editions +will be renamed.</p> + +<p>Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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