AP_Physics_B_-_Electromagnetic_Induction (1).ppt

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1、ElectroMagneticInductionAPPhysicsBWhatisE/MInduction?ElectromagneticInductionistheprocessofusingmagneticfieldstoproducevoltage,andinacompletecircuit,acurrent.MichaelFaradayfirstdiscoveredit,usingsomeoftheworksofHansChristianOersted.Hisworkstartedatfirstusingdi

2、fferentcombinationsofwiresandmagneticstrengthsandcurrents,butitwasn'tuntilhetriedmovingthewiresthathegotanysuccess.Itturnsoutthatelectromagneticinductioniscreatedbyjustthat-themovingofaconductivesubstancethroughamagneticfield.MagneticInductionAsthemagnetmovesb

3、ackandforthacurrentissaidtobeINDUCEDinthewire.MagneticFluxThefirststeptounderstandingthecomplexnatureofelectromagneticinductionistounderstandtheideaofmagneticflux.FluxisageneraltermassociatedwithaFIELDthatisboundbyacertainAREA.SoMAGNETICFLUXisanyAREAthathasaMA

4、GNETICFIELDpassingthroughit.ABWegenerallydefineanAREAvectorasonethatisperpendiculartothesurfaceofthematerial.Therefore,youcanseeinthefigurethattheAREAvectorandtheMagneticFieldvectorarePARALLEL.ThisthenproducesaDOTPRODUCTbetweenthe2variablesthatthendefineflux.M

5、agneticFlux–TheDOTproductHowcouldweCHANGEthefluxoveraperiodoftime?Wecouldmovethemagnetawayortowards(orthewire)WecouldincreaseordecreasetheareaWecouldROTATEthewirealonganaxisthatisPERPENDICULARtothefieldthuschangingtheanglebetweentheareaandmagneticfieldvectors.

6、Faraday’sLawFaradaylearnedthatifyouchangeanypartofthefluxovertimeyoucouldinduceacurrentinaconductorandthuscreateasourceofEMF(voltage,potentialdifference).SincewearedealingwithtimeherewereatalkingabouttheRATEofCHANGEofFLUX,whichiscalledFaraday’sLaw.UsefulApplic

7、ationsTheForeverFlashlightusestheFaradayPrincipleofElectromagneticEnergytoeliminatetheneedforbatteries.TheFaradayPrinciplestatesthatifanelectricconductor,likecopperwire,ismovedthroughamagneticfield,electriccurrentwillbegeneratedandflowintotheconductor.UsefulAp

8、plicationsACGeneratorsuseFaraday’slawtoproducerotationandthusconvertelectricalandmagneticenergyintorotationalkineticenergy.Thisideacanbeusedtorunallkindsofmotors.Sincethecurrentint