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1、TelegraphKeyandSounder(AnElectromagnetismProject)Introduction:Telegraphisoneofthefirstapplicationsofelectromagnet.Inthisprojectyouwillmakeatelegraphkeyandsounder.Materialsforthisproject(shownhere)areavailableinallversionsofMiniScienceElectromagnetismKits.
2、?Baseboard?Magnetwire?Keyandsoundermetalstrips?Nailandscrews?BatteryHolderAdditionalmaterialsinthekitareforotherprojects.HistoryoftelegraphTheBeginningofElectronicCommunicationsIn1825,BritishinventorWilliamSturgeonexhibitedadevicethatlaidthefoundationsfor
3、large-scaleelectroniccommunications:theelectromagnet.Sturgeondisplayeditspowerbyliftingninepoundswithaseven-ouncepieceofironwrappedwithwiresthroughwhichthecurrentofasinglecellbatterywassent.In1830,anAmerican,JosephHenry,demonstratedthepotentialofSturgeonf
4、sdeviceforIongdistancecommunicationbysendinganelectroniccurrentoveronemileofwiretoactivateanelectromagnetwhichcausedabelltostrike.Thustheelectrictelegraphwasborn.SamuelF.B.Morse(1791-1872)successfullyexploitedHenryfsinventioncommercially.Whileaprofessorof
5、artsanddesignatNewYorkUniversityin1835,SamuelMorseprovedthatsignalscouldbetransmittedbywire.Heusedpulsesofcurrenttodeflectanelectromagnet,whichmovedamarkertoproducewrittencodesonastripofpaper-theinventionofMorseCode.Thefollowingyear,thedevicewasmodifiedto
6、embossthepaperwithdotsanddashes.Hegaveapublicdemonstrationin1838,butitwasnotuntilfiveyearslaterthatCongress(reflectingpublicapathy)funded$30,000toconstructanexperimentaltelegraphlinefromWashingtontoBaltimore,adistanceof40miles.Procedure:Thetelegraphbasebo
7、ardinthekitcomeswithsomepilotholesonthefaceoftheboard.Usethediagramimageintherighttomarktheholeswithletters.Thiswillhelpyouinthenextstepswhereyouneedtoconnectwires.ThenailholemarkedwithNisathroughholethatcanbeseenfromthebackoftheboardtoo.Insertthelarge(3M
8、nail)intotheNhole?Thenailshouldnotexitthebackoftheboard.LaterwhenyouinstalltheZshapesounder,itshouldbeabout2mm(1/8ofaninch)abovethenail.Thisnailwillbethecoreofyourelectromagnet.Wrapsomemaskingtapearoundthenail.Maski
