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AUTHOR Horton, Robert L. TITLE Science Fun with ...Discoveries and Innovations. INSTITUTION National Center for Science Teaching and Learning, Columbus, OH.; Ohio State Univ., Columbus. Cooperative Extension Service. SPONS AGENCY Office of Educational Research and Improvement (ED), Washington, DC. REPORT NO FS-4-H-531 PUB DATE Sep 93 CONTRACT R11700062 NOTE 49p. AVAILABLE FROMNational Center for Science Teaching and Learning, 1929 Kenny Road, Columbus, OH 43210. PUB TYPE Guides Classroom Use Instructional Materials (For Learner) (051)

EDRS PRICE MF01/PCO2 Plus Postage. DESCRIPTORS *Electric Batteries; *Electricity; Elementary School Students; Intermediate Grades; Physics; *Science Activities; Science Education; Science History; Scientific Concepts; Secondary Education; Secondary School Students IDENTIFIERS 4 H Programs

ABSTRACT This project manual is written for 4-H member children who are in the fifth grade or older. This project is designed to familiarize members with the scientific history concerning the discovery and application of electric energy through the 1800's. Readers can conduct experiments similar to the ones performed by the scientists and inventors of that day. Topics include , current electricity, , , electric generation, electric motors, and electric light.(PR)

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EDUCATIONALOnce of Educations! RESOURCES Research and INFORMATION Improvement U.S. DEPARTMENT OF EDUCATION CENTER (ERIC) 0 Minorgc. Thischanges documenI have been hes made bmnreproductionoriginatingreceived toreproduced improve from ii quality the s meson of otganmation OERImen!Points positiondo ol viewnof CPnecessartly or POItCYopinions statedreplesent in !his oehciel dot u- 3 WITH . . SCIENCEDISCOVERIES AND FUN INNOVATIONS ELECTRKITY TABLE OF CONTENTS1.MEMBER STATIC PROJECTELECTRICITY GUIDE 83 BY ROBERT L. HORTON, PH.D.Extension 4-H Specialist, Science Education, 4.2. 3.CURRENTELECTROMAGNET ELECTROMAGNETISM ELECTRICITY 151210 Thecuriosityand Ohio the Statekids and ofwillingnessUniversity the neighborhood to try. for theirThis invaluable book is dedicated to my daughters Christy, Carrie 6.S. 7.ELECTRIC ELECTRIC GENERATIONMOTOR LIGHT 221719 ResearchgrantNational #R117Q00062 Center and Improvement, for Science TeachingU.S. Department andDevelopment Learning of Education underof this project was supported by from the Office of educational the 0 For Sale Publication TheReeder, Ohio State Extension University Specialist, AgriculturalAdditional Engineering, technical support provided by Randall basisAll origin,Extensioneducational without gender, Serviceregard programs age, to are disabilityrace, availableand color, activities or Vietnam-eratocreed, all conducted potential religion, veteran clientele sexualby the orientation,Ohio on a Cooperativenondiscriminatory status. national Issued9/93-3M-110088Director,1914, in infurtherance cooperationOhio State of University Cooperativewith the U.S. Extension. Extension Department work, of ActsAgriculture, of May 8 Keith L. Smith, and lune 30, 2 SCIENCE FUN WITH ELECTRICITY 4 5 MEMBER PROJECT GUIDE YoungerPROJECT members BACKGROUND may take this projectThis under beginning the supervision level project of an is adult. written Due for tomembers the who are in the fifth grade or older. andActivity.Thistechnical activitieswill Itallow nature will in alsothe one of individualhelpthe year. project, reduce to membersexplorethe costs thoroughly mayassociated focus each on with a experimentfew completing of the Activities andall the Digging experiments per year. Deeper ductthe discovery experiments and similar application to the of ones electric performedAsThis energy members project by through theis move designed scientists the through 1800's. to and familiarizethe Membersinventors manual members they ofwill that con-will day. notewith thatthe scientificthe experiments history concerninghave been scientists,organized tochronologically build upon previous to their discoveries. placeMembers in history. should This allowsalso note the the members, timeline like which earlier runs through the book. It provides a . PROJECT1. GUIDELINES Complete the Planning Section of this guide (steps 1-4). eventsonbasicsgraphic the sceneoftoward representation electricity to the apply end had this of ofbeen thethenew 19thlearned,historical knowledge. century inventors development asThis compared islike evident Edison of electricity.to by the and the beginning. Morse abundance Note quickly that In factonce appeared things the of dates and 3.2. CompleteExploreInterest each Areaat leastof selected.the one Project of Diggingthe Ink.i experiments est Deeper Areas. Activities for each are project,were happening especially so if fast you that choose only toa fraction participateCheck of your the in countyimportantcounty projectproject events guidelinesjudging are listed. or forprepare additional an requirements for taking this 4. Build a DC motor from scratch or fromforoptional. details.a kit. See page 20 nextexhibit level for ofthe 4-H fair. electric Members energy who projects. complete this project are encouraged to move to the 6.5. Takeactivities.Become part in involved at least intwo at Organizedleast two Citizenship/Leadership Project Activities. 6 SCIENCE FUN WITH ELECTRICITY 7 PLANNING YOUR PROJECT Date Completed 1. STATIC ELECTRICITY, page 8 Interest Areas ad Activities StepsPROiECT 1 and I NTE 2 R E ST AREAS 2. CURRENT ELECTRICITY, pageExperiment 10 12 Static Electricity Light Charge a Balloon ANDto Interestcomplete ACTIVITIES Area. at least Digging one ofDeeper the experiments ActivitiesExplore are optional. each of the Project Interest Areas listed. Plan in each DiggingExperiment Deeper 3 Tongue Test GettingPotato Electricity Polarity Indicator From a Lemon complete.Have your parent or advisor initial and date what you 3. ELECTROMAGNETISM, page 12Experiment 54 Carrying Wire MakingMagnetic a GalvanscopeField Around a Current 4. , page 15 DiggingExperiment Deeper 6 Make an Electromagnet Polarity Check 5. ELECTRIC GENERATON, page ExperimentDigging17 Deeper 7 Induce Current From a MagnetMagnetize a Screwdriver 6. , page 19ActivityDigging Deeper Magnetic Force AC/DC Detection 7. ELECTRIC LIGHT, page 22 Experiment 89 LightBuild a CoiledDC Electric Strand Motor of Wire 4 SCIENCE FUN WITH ELECTRICITY REPORT OF ORGANIZED ACTIVITIES nizedbelow,ORGANIZEDStep Activities and3 plan chart. your PROJECT involvementBefore starting inArrIvrnEsSelect theyour Report projecttwo of of thewrite Orga- organized project activities listed Plan To Do Date Completed Interest Areas and Activities when.youranyhave choices time.Organized taken inpart the Activities in section an activity, maylabeled berecord Planadded what To or Do. changedyou Once did and youat A.,04,teath, 5/28Date: Aoeehry 9 electek mat ccioweiclaxeidees Wiat/Pd: CountyDemonstration Judging Sample Organized Activities SpeechIllustrated Talk awmed TourMallFieldProject ShowTrip Exhibit WorkshopProjectShortRadio/TV MeetingsCourse Presentation

1 0 SCIENCE FUN WITH ELECTRICITY 11 5 StepLEADERSHIP/CITIZENSHIP 4 Check ACTIVITIES the activities you wish to do or plan your own Leadership/CitizenshipEncourage someone to Activities When I Finished take an electric project. addedareprogressin the through. space or bychanged marking Leadership/Citizenshipprovided. at any Do time. at least two. Keep track of your the date (month and year) when you activities may be InviteOrganizeHelp someone someone an electric with to talk hissafety to or your her electricclub on project.electricity. clinic in your community. TeachPrepareelectricity. someone and exhibit something or poster you learned about about electricity. benefitApplyEncourageHelp something ayour member a family. friend youprepare to learnedjoin his4-H. orabout her electricity electric project for to PlanHelp youra member own activities prepare here.an electriccounty fair. exhibit for the

SCIENCE FUN WITH ELECTRICITY 1 3 partparent,local PROJECTof aproject more comprehensiveadvisorreview. REVIEW orThis interested review member canadult.Once take It may youpart complete with your what you planned, arrange for evaluation at a also be thisyourdesignedtime level agreedgrowth ofto evaluationhelpasupon a you4-H by clubevaluatemember. can members. receive what special youSuch learned evaluations membership as well are as Members who take part in projectcertificates.and project judging. achievement However, awards this level like of ribbons, evaluationIn addition, pins deter- and you may want to take part in county best"youthemines a inachievements"project your "how project grade."well" youarea,of Youothers did as on well in your order as projectpossible to determine by state assigning fair"the will also be compared against Memberparticipation. Recognition For more Program, information or contact refer to your 4-H local 956, 4-H Nopwrizemzermivermrezierzerzfffriliweweizezzrzerzewzrizeizezrzet,::II '4'NN, NRi Extension office for specific county project judging infor- 44N .444144 mation. ,NN.44 Congratulations to... N'41'444 N..,44 her SIR Ce.`qiilly ph11111ing Ulla «)Illphil Ilg the ,hh.NiNNI N.,ZNZ BEGINNING LEVEL 4-H PROJECT h.N,N. N 4441 ()ft i n .4 1 hp (gull ,%late I ' plitym I I. ErtellAtmi 44hN1% 4, 0,..4 N4144 T H E if4N tN et.s' Agate! II tat F1 UMV,ICITY4( N 1 4 SCIENCE FUN WITH ELECTRICITY 1 5 7 a dark room is the The simple act of flicking a switch to turn on a lamp STATK ELECTRIMY result of centuries of investigation and in . Experiment 1 experimentation.ofandlights people, produces and heatsbegan convenience The our more sciencehomes, than andoperates2,000of electricity, entertainment years complex ago in the power that formachinery millionsancient CHARGEwork. A BALLOON Try this experiment to observe static electricity at . comedifferent into contact,materialsWhen any two jewelry.amber,Miletus,Greece. a bornWhenThere, plastic in rubbeda640 type scientist BC, of briskly materialobserved by the with commonlyname anfur, of unusual propertythe amber of wouldThales of used for Youquickly will against need: a piece of InflatePieceRubber ofthe balloon wool balloon, or fur tie its neck securely wool. Now hold the and rub it ""electricitytiny move particlescalled of attract"static bits electricity." of cloth, wool "Static" and meansfur. "still,"What or the "not Greeks moving." observed was something called basis for the .:. balloonExplanation against the wall. It will stick. Rubbing the balloon removed some of the free . both materialsother.electricfrom This onean givescharge. to the wordThisTry early "electricity."Experiments Greek discovery Their 1 & 2 name to alsoexplore for provided amber wasthe this discovery. "." electronswithWhennegative the the from uncharged charge charged the andwool. balloonwall, the This woolit exchanged wasgave a broughtpositive the balloon in contact a electrons withcharge. electronsObjects become that gainnegative while Questionthe wall, causing it to stick. Explain what happens when you get "static .a electronsobjects become that lose positive. off,area.shockin negative the Why summer? does or positive? this What happen type more of charge are you giving " in the winter after walking across a carpeted in the winter than 9 el, 8SCIENCE FUN WITH ELECTRICITY 1 6 Timeline Ma640 les BCof Miletus discovers static electricity. 1 7 EXPERIMENT 2 staticpractical electricity. progress In began that year, with It wasn't until 1600 that Fig. 2 Staticelectricity machine electricity.STATIC ELECTRICITY LIGHTTry this experiment to observe the power of static thatattractionGilbertEnglish century described physician in amber.(1663), the William Later Ottostatic Y ou will need: DarkPieceFluorescent room of wool tube ematicianmachines.Vaninvention Guericke named This of thebuilt was PieterLeyden one followed ofvan Jarthe Musschenbroek inby 1745 Dutch by math- the first static electric woollight. cloth as shown below. The tube Inwill a darktry to room, rapidly rub the tube with the chainwithinsertedHe metal coveredprovided afoil. brass a Through contactthin rod glass with withthe jar a wrapping, thehookinside inner at and top. foilhe out A wasdeviceandbefore thea very would ground. this important timestore Musschenbroek no electrical discoverymethod charges.had because found been This thefound Explanation The friction between the wool and the glass tube for storing static charges. An equally important discovery StoresFig. 3 Leyden electrical Jar charges 14" givelodgedatomscaused off in electronsultravioletelectrons the gas insidetry torays. striketo get Thesethe and backtube. raysdislodge into When strike their electronsthese aatoms, phosphor dis- theyfrom "electroscope."Bennetnamedoccurred Abrahamperfected in 1787 An Bennet.bywhat electroscope an heEnglish In called that scientist yearhasthe two coating on the inside of the glass tube, which causes the coating to glow. thestripsmetalvessel. leaves of ballmetal A to chargedon repel foil top hanging eachof amber the other. instrument inside rod Thistouching a glass causes the ElectroscopeFig. 4 aspresenceinstrument determining of electrostatic was the useful polarity forcharges of determining the ascharges. well the propertiesPetrus1296 Peregrinus ofAD magnetism. discovers 1 8 TheGreek1600 word word "electricity" "electron" coined by William from the Gilbert. : firstOtto1663 static Van electric Guericke machine. builds the SCIENCE FUN WITH ELECTRICITY 1 9 9 - CURRENT ELECTRICITYIn 1786, Luigi Galvani observed how a frog's legs Tongueown source TestExperiment of 3 Make and test your electro- nikik,4kif. '464 it .41., Inside the battery is observedmovedactionzinc instruments,when had that exposedsomething when theyhe to touched alsotoa strongdo with the static legs charge. moved. He concludea that the the "static electricity with copper and He also chemical electricity. ( ir a carbonzinc container rod and to trappedhis work in themade frog." other scientists aware Althc 'gh his conclusion was wrong, of this unusual produceflows if anthecharge. electric rod and A current container are occurrence.Galvani'sdiscovered discovery why the frog'swas a legs new moved. form InHe 800, Alessandro Volta, an Italian physics professor of electricity which dc,Irmined that : You will need: 1 zinc carbon battery (general purpose type) used up, theconnected. batterychamicals When are goes dead. coupledactiongeneratedhe called of withmoisture "currentfrom the the copper in electricity."chemical the frog This type and of electricity was high copper content) CopperHand pennytools (Best if minted before 1980 due to zinc zincled instruments. Volta to produce the first Further experimentation thec..rbontongue. container battery. Touch and Wash the the container thoroughly.With help from an adult, take apart a the coin and container together. clean copper penny on your them apart and it YouPlace CarbonChemicals rod electricitysourcezincmade plates of it of continuous-- stackedtheseparated battery. copper current by paper and He willstops. feel a tingling sensation. Move containerZinc sourceor referredincloth a salt of that battery solution.to had as a power "voltaic This wasearly cell." been soaked Explanationsalivasmallare placed electricis slightly in saltycurrent salty, water flowsso the between coin The container is made of zinc. and connected together, a and containerif zinc and copperthem. Your Fig. 5 Zinc carbon battery TryexploreDigging Experiment thisDeeper discovery. 3 Activities toand the two Fig. 6 Voltaic cell . causeproduce your a weak tongue current. is very 5 You feel thissensitive. current be- 10SCIENCE FUN WITH 20 ELECTRICITY of1729Stephen conductors Gray discoversvs non-conductors. the idea charges1733Charles Durepel Fay and discovers unlike attract. that like static1745Pieter electricityVan Musschenbrock can now be develops built up the Leyden 2 1 and stored. Jar; GETTINGDigging Deeper ELEaRICITY FROMTry Amaking LEMON electricity from a natural power source. You will need: PaperLemon12 feet clip 22-gauge insulated wire, single strand Stripped copper wire usedimmersedlemon. for This the in cell electrodesan consistselectrolyte. so of the twoTwo electrolyte electrodes, differentAnother (lemonmaterials separated form juice) of are a and voltaic cell can be made by using a the termsFranklinand "positive" "negative"originated for In 1750, Ben willand act produce more on a one potential electrode difference than it between doesHere on isthem.the how other to make the cell: Roll the lemon on a Lemon, orange or grapefruit Opened out paper clip electricalciHe scoverod is said polarity. to the have bi. waytissue.pushhard into Straightensurfaceit theinto lemon. the with lemon the yourClean paper near palm the clip, the toinsulation paperandbreak push clip.up off someit 13oth theabout wire,of wires halfthe and from the lemon. You will taste slight acidity. You may electricity duringpole OMexperiments his nature of with lightning. His itinsertinginsideshould may beor be theoutsideinserted close wire, to the morefirste(. lemon. .,n make easily. other Ifa youbuthole shouldhave with anythe not paperdifficulty be touching clip so mentofcaneven a experience9 feel withvolt a an() slight orange by tingling. touching orbattery. any This otheryour Youis the tongue citrusmay same alsofruit. to sensation the try terminalsthis experi- you lighting experimentsalso led way toinvention his of thelightning rod. touch your tongue to the ends of the twoTo wires find whether that come the lemon is a source of electricity, 1. A toBen electricity1750 Franklin andgives invents + and lightning rod. '2 designations electricity"Galvani1786 inadvertently while experimenting discovers "currentwith frog. SCIENCE FUN WITH ELECTRICITY

insulationtheFig. cardboard 13.1 Wrapfrom andthe the ends.remove wire around the coilFig. of13.2 wire. Place Align the the compass wires east inside and west. the andFig.reversing watch13.3 Touch the the compass wiresthe wires to needle.see to whatthe Alsobattery happens. tty 111 1827 between Faraday1831 discovers generation of 14SCIEN9E . FUN WITH ELECTRICITY r) 8 theWilliam1825 electromagnet. Sturgeon invents current,George Ohmvoltage discovers and resistance. relation 4. n electricity by use of "Disk Dynamo." 6 5 4 3 1 1.11111111111 Without question, the greatest immediate practical ELECTROMAGNET DiggingPOLARITY Deeper CHECK Check the polarity of __ P2r 4ofThisapplication 1819)Woolrich, was was accomplished of Englandthe Oersted's eventual wound discoveryin invention1825, copper when (electromagnetism, of wire the William aroundelectromagnet. Sturt, a bar on of tromagnetcompass.yourinches electromagnet from Holdone the toyour twocompass withelec- a as motormadeiron thepossible.and telegraph, made His the electricfirst electromagnet. wasgenerator, made fromand This thea softinvention electric iron bar theshownmove polarity. in the Figure nailNote and14.2. the recheck dif-Re- Using a battery operated aboutfurther"U" shape.12-inches explore Try longExperimentthis innovation.and 1/2-inch 4 and in the diameter Digging bent Deeper into toa timetheference of availablenail the wasin compass. the inmagnetic deflection place, When all telegraph in 1837.electromagnet,Samuel Morseinvented the andstrength around was the funneled nail. in watchFig. 14.2 electromagnet Tap on terminal attract and message,God "Whatdistance wrought?" hath telegraph was The first long MAKEExperiment AN ELECTRoMAGNET 6 Experience the power of an electromagnet. heldFig. 14.1in place Magnet with wiretape needle WashingtonsentSupreme D.C.from ontheMay CourtU.S. 24, in1844 to You will need: Large1 6-volt nail lantern(about three battery inches lon,4) inMagnet place wirewith heldtape energizedIn an early by lectromagneticMorse a current telegraph, pulse coils (1) Baltimorewere MD. around the nail as shown in Figure4 feet 14.1. ofLeaving 22-gaugeLeave a a few little insulated inches wire at ofwire, the wire endsingle for a strandlead, wrap about 50 times re- striprollerleverlinetransmitted (2). (5) (3)(4) The driven thatagainst through coitspressed by aattracted amoving aclockwork antelegraph inked papera thefor anotherelectromagnet lead. When can pick the endsup small of the nails coil and are paper connected clips. to a battery, 11 Pins or tacks fliotor wound by a handle (6). inventsJoseph*1833 firstSaxon AC of generator. 3 0 throughWilliam*1834 Sturgeon invention perfects of split ringDC generatorcommutator. electricDavenport*1835 motor patent's (battery-powered). the first DC SCIENCE FUN WITH ELECTRICITY 3 1 15 i MAGNETIZEDigging Deeper A SCREWDRIVERUse electromagentisim to magnetize a screwdriver. fieldintoEXPLANATION of a the magnet. coil aligns (Fig. the15.6) molecules (You canYou have made a permanent magnet. accomplish theof same the screwdriver The magnetic Man-made magnets are aluminum, You wiii need: Screwdriver6-voit lantern battery fewremaindownwardthing hours, by rnagnitized stroking daysfashion.) or the yearsfor Itscrewdriver awill with a Ell 011Ell Ell Ell Ell Ell EllEll Ell EllEU bar magnet in a electromagneticallynickel and cobalt(alnico).charged Once this around15.1 the ). Useshank all ofthe the wire screwdriver except for 25in another Leave evenfeet of coils a 22-gauge length of insulatedwire for a wire,lead, then wrap single strand short length for the wire (Figure dependingtheThefrom longerharder which on it theitthe will was material, materials remain made. f3clice11341a1firill011 CI El EN Ell GM Fig. 15.6 metal will remainextremely hardpermanentlymagnetized, driver.battery(Figurea lead. Remove(Figure15.2). Briefly 1 the 5.3). touch This shouldthe ends magnetize to the the screw- insulation from the ends of the leads terminals of the magnetized.a hammer. (Fig. 15.5) To remove the charge, try striking the This will jumble the atoms that ONNic-alVilEEN Fig. 15.7 (Fig.screwdriver 15.7) with outlastingsteel softer magnets. 411111IIMININ were aligned in the magnetizing process. 4:1.110". ..."-al.10101040" chargedFig. 15.4 magnetScrewdriver becomes a Fig. 15.1 Wrap wire Fig. 15.2 Cut, leaving a leader Fig. 15.3 Connect the wire to battery Fig.to 15.5 disengage Strike screwdriviermagnet 16SCIENCE FUN WITH ELECTRICITY 32 Samuel1837 Morse invents the telegraph. betweenFirst1844 long-distance Washington, telegraph D.C. and system Baltimore, established Md. 33 IONE WAY> D.C. Current ELECTRIC This(DC) meantlike that that of currenta battery. A.C. Current 5 andiscovery.scientist electric named Hecurrent found Michael in thatthe Faraday coila moving of his made galvanscope.magnetIn an 1831, important would while induce using a type of galvanscope, a youngGENERATION meantLaterremainedtion;flowed positive generators thatin thepositive the alwayssame current produced and direc- negativewent an back alternating always and forth, remained current alternating (AC). negative. This the In the United ACStates, currentthis turnabout makes 60 These"dynamoFaraday's early electric discovery generators machine" led producedto the or rapidthe a electric simpledevelopment generator. of the polarityDiggingmitted of over Deeperthe longerpoles. Activity distances.This allowedto explore Try electricity Experiment this discovery to be7 and trans- further. the thnes each second.standard allowsThis 60-cycle - Experiment 7 ...... INDUCE CURRENT FROM UseA MAGNET your galvanoscope to test the presence of . makelarger a coilthan as the shown bar magnet. in Figure Leave 17.1. a ItlengthWrap should thefree be wire at a eachlittle around end your fingers about 30 times to electricaland appliances electric motorselectric clocks, to operate Youelectricity win that need: you create. Bar10 magnet feet of 22-gauge insulated wire, single strand outeterto insulationmake of (see the connections. Figure center on each 17.2). of the end Remove Move coil and as the connect shownahout bar magnet a inthem half Figure inch toabruptly the 17.3. of galvanom-the in and consistently across the country. (bell wire) Galvanoscope Notice the direction of the movement of the needle. needlepushedWhen the is into deflected magnet the coil, is in firstthe one direction.tion.movesmagnet The in Whenis currentthe removed, other the changed direc- it magnet,creasedThedirections current bymoving (Figure using can bethea 17.4). stronger in- S Fig.171 Make0 a coil of wire. theFig. coil17.2. with Connect the compass. the coil to theFig. coil 173 and Quickly watch push the compass the magnet needle. into moremagnet loops faster in orthe adding coil. ismagnetFig. deflected 17.4. and Quickly innotice the withdrawopposite that the dilection.compassthe S S S S I theManufacturing1850 place of "hand of wire drawn" by machine methods. takes 3 4 firstZ'enobe1873 DC motorTheophile to be Gramme powered demonstrated by a generator. theAlexander1875 electric Bell telephone. develops SCIENCE FUN WITH ELECTRICITY 3 5 17 AC/DCDiggingDC currents Deeper',DICTION differ. Try this experiment to see for yourself how AC and postofDirect one of batterythe Current other to battery.the positive Wire the negative post When the first AC You will need: 1/2cup2 teaspoons2 teaspoons water cornstarch of potassium iodide (obtain from phar- outerfreeandTurn negativeconnect arim pie of pan the apost wire upsideplate. to from the down, the inventedunderstood in 1833 how itgenerator it waswas not fully macy, or call NASCO at Measuring82 metalfeet bell (non-aluminum) wirecup pie pans 1-800-558-9595) aclothoneSqueeze wire cloth over to theand the remainingsolution stretchplate. Attach out of the could be useful. ClothACMix2 train6-volt stripstwo transformer lanternteaspoons batteries of cornstarch in th-cup of water. ofpositive lineitthis across willwire post. appear. theas Using acloth. stylus, theA soliddraw tip clothAdd two in the teaspoons solution. of potassium iodide. Soak the strips of formerAlternatingAttach instead a wire of from batteries.Current the low- Use an AC train trans- saturatedofvoltage plate.a pie plate.terminalConnect in solution Spread toa wirethe on a rim clothtothe the outlet.transformertransformer,unused Holding terminal intoand the anofplug insulatedtheelectric the theform.cloth.part wire of A quicklythe broken free across wire, line will drawthe 18SCENCE FUN WITH ELECTRICITY 3t; setFirst1878 up commercial in Somerville, telephone Mass, line theCharles1879 knife Scribner switch. invents 3 7 electricEdison1879 inventslight bulb. the MAGNETICActivity FORCE Imo=scrambledreliable electric to harness current these had newbeen powers. discovered,Now As thatearly inventors the as generation of electromagnetism and ELECMIC MOTOR 835, other,tryusing making twothen bar themattract magnets. repel each each First, See how a motor works eries.Thisthean American world'sIn invention 1821, first Faradayscientist was DC based electric learnednamed on (battery-operated) another Thomasthat electric of Davenport Faraday's current motor. coulddiscov- patented 3 other.likenorthnetism.ing istheWhat andthe Eachearth. principleyousouth magnet Theare pole, observ- likeof has mag-just poles a create mechanical motion or a type of "moving magnet." coil)Hisaround device which a wasmagnetwould a wire rotate when ( Fig. 21 Polarity change of AC motors do not have split ring commutators. This is D.C. ma`or E*1111 N magnetsoppositerepel(N/N, eachS/S) polesattract. ofother, the (SIN) That'smagnetsjust ofas whythe the electromagnetDavenport'sFaraday'swas applied. invention, motorHowever, in place utilized ofunlike a an Experimentancurrentbecause AC motor automatically. Alternating 8 is to set further up Current asBecause explore separate reverses ofthe rings.this, invention the the (Figure polarity of 21.2)the of theD.C. Try in turnsprovidingareofa motorthe in the statorconstant works. rotor.the and force (Figopposition;The rotor that 21)polarity poles motor'snatural magnet, potential increasing power. the A motor is simply two Motor.C-A71PLE Fig. 21.1 D.C. MOTOR Statorconstant (D.C. Electro but opposite magnet) rotorPoles poles Fig. 21.2 A SIMPLE A.C. MOTOR A.C. Electra magnet opposite to Polesrotor alternate orstator,tion. . The while stationary theA basic rotating magnet electricFig. 20electromagnet Earlyor motor electromagnet D.C. consists Motor is called of is called the rotor the magnets working in opposi- only four main parts: , rotor/armature, commutatorT here and arebrushes. two types of motors those that operate on ring commutator Split Commutators magnetCurrentstationaryDirect (AC).keepsCurrent magnets. A trying DC (DC) motor to andWith line worksthose eachup opposite that becausehalf operateturn, poles the the onspinning withsplit Alternating thecontacts constant Poles I II vf..armature BrushRotor/ polarityof the commutator of the rotor. function (Fig. 21.1) automatically to change the \IIIIMMIOINtle2 D.0 power source A Brush AL. power source Edison1880 patents the glass enclosed fuse. 3 8 plantFirst1882 DCput municipalinto operation. power startedFirst1883 electric in the street U.S. inrailroad Baltimore, was Md. SCIENCE FUN WITH ELECTRICITY' 3 9 19 ExperimentBUILD A PC 8 ELECTRIC MOTORBuild the same type of "moving magnet" originally Tape ARMATURE , discoveredavailabletilekit. statorThis includes byratherand Faraday. can than motors be a obtainedYou magnet. that may use fromalso an abuildelectromagnet hobby one store, toy Several good kits arc from a for electric motors were Prior to 1873 all , Ycallingstore, ou the NASCOwill Boy need: Scouts at 1-800-558-9595. of 15 feet of 22 gauge electric motor wire America Supply Catalog or by Commutatorbared wire I That is Theophileuntil Belgianscientistbattery Gramme powered. Z'enobe ThinTape1 plastic 6-volt lanternor wooden battery rod Tape 01'00,100 Commutatorbared wire 2 Tape Tape demonstrated that a motor couldpowered be by a 4 nailsBarBlock magnet of wood (or electromagnet) Crossed nails generator. HammerKnifeBroomUsing handle the copper wire, make a neat circular coil by windingbyshapeRemove binding 30with theturns itprojecting coilsparingly of and the flatten wirewire with its windings, to ends. Keeplittle the piecesaround coil inof shapeasticky broom tape. handle. make a ring theinsulation coil. Attach from the ends of thethe barewires wireStick projecting on the opposite coil on the rod as shown. Scrape away from Bar magnet Fig. 24 , coilwiressides is ofarecalled the called rod, the commutatorusingarmature. thin bands contacts of tape. (1 The exposed and 2) and the OOOOO OOOOO 20SCIENCE FUN WITH ELECTRICITY () theElihu1885 circuit Thomson breaker. invents . " electricalEChu1886 Thomson welding patents system. Ifit plantFirst1886 ACput municipalinto operation. power place) between two pairs of crossedMount the rod (with its armature and commutator in nails or a block of What Can Go Wrong? AToo badly-balancedShort-circuitingthey much touch friction ofarmaturewith current the crossed coilbetween nail wires bearings 1 and 2 if tureunderwood. as the(See it is armature spun.Figure 24.) where Put ait willstrong not bar obstructMake magnet twinthe just arma-leads from thin wires and connect them ThePoor Insulationmagnet battery placed notconnections scraped too far awayoff of fromcommutator the armature wires contaCtscommdtatorto)ainches 6-volt towith battery. make contacts the sidesbrushes Bare 1 andoftheir thefor 2 other theonbrushes, amotor. endslevel. which forSetTouch the you rod hold with about 2 the mentalExperiment DC motor;8, you sincemade ita operateslikeness ofonThere Faraday's dircct are current. many experi- kinds of motors. If you completed .whilevertically.tator.spinning. you hold The If thenot, motor brushes have should someone in startplace giveby against itself the spindlethe commu- a turn and keep Therecurrent) are alsoand aremotors used which around operate the home on AC and (alternating in businesses.

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