双语物理教案.doc

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1、HOWDCELECTRICMOTORWORKSIntroductionManypeoplearefamiliarwithDCmotors.Ifyouhaveeverhadanelectrictoytrainorcarasachild,youmayknowhowaDCmotorworks.Electricmotorsareeverywhere!Inyourhouse,almosteverymechanicalmovementthatyouseearoundyouiscausedbyanDCelectricmotor.Byunderstandinghowamotorworksyoucanlearn

2、alotaboutmagnetsandelectricityingeneral.Lookaroundyourhouseandyouwillfindthatitisfilledwithelectricmotors.Here'saninterestingexperimentforyoutotry:Walkthroughyourhouseandcountallthemotorsyoufind.Startinginthekitchen,therearemotorsin:Inthisactivity,studentswillbuildanelectricmotormodel.Afterthishasbe

3、ensuccessfullyaccomplished,studentsenjoyholdingacontesttodeterminewhosestructurecanturnmoresteadily.BackgroundManypeoplearefamiliarwithDCmotors.Ifyouhaveeverhadanelectrictoytrainorcarasachild,youmayknowhowaDCmotorworks.Ifyouwerelikemeyouprobablytookoneapartandcouldn'tputitbacktogether.Ifyoueverhavet

4、hechancetotakeapartasmallDCelectricmotor,youwillfindthatitcontains:·Armature·Commutator·Brushes·Axle·Fieldmagnet·DCpowersupplyofsomesortTheabovefourpicturesshowhowanDCelectricmotorworksinacircle.TheprincipleofDCelectricmotoristhatthecoilwithcurrentcanturninthemagneticfield.Theusageofconnutator:Tocha

5、ngethedirectionofcurrentinthecoilwhileitpassesthebalancedpositionsothatthecoilcanturncontinuously.Materials1.Battery2.Varnishedwire3.Magnet4.Paperclip5.Sandpaper6.FoamedplasticQuestions1.This“electricmotor”hasnocommutator.Whycanitturncontinuously?2.Whichhalfpaintisbettertobescraped?Youcanwindseveral

6、coilsandscrapepaintatdifferentpositions,thentrythemtofindwhichisbetter.