电子专业英语教学课件作者高明辉第10章.ppt

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1、Warming-upI.Canyouexplainthefollowingpicture?II.Doyouknowthemeaningofthefollowingphrases?1.inducedvoltage2.electromagneticInduction3.magneticfieldUnit10ElectromagneticInduction下一页返回III.TalkaboutCurrentinEnglish.Andthefollowingpatternsyoucanuse:Doyouknowwhentheelectrom

2、agneticinductiontakesplace?Couldyoutellmehowtheelectricityisgenerated?Howtocallthegeneratedvoltagesfrominducedvoltages?Doyouknowwhofirstdiscoveredtheinducedvoltage?Haveyoueverheardofthephrasethelinesofforce?TextComprehensionElectromagneticinductionThegenerationofelect

3、ricityisaprocessofchangingenergyfromsomeotherformintoelectricalenergy.Andthemostpracticalprocessistoconvertmechanicalenergyintoelectricalenergy.Generators,electricmotorsandtransformersalldependonelectromagneticinduction.Unit10ElectromagneticInduction上一页下一页返回In1831,Mic

4、haelFaradayinEnglandandJosephHenryintheUnitedStatesdiscoveredthatvoltageisinducedacrosstheterminalsofaconductorwhentheconductorismovedacrossastationarymagneticfieldorwhenthemagneticfieldismovedacrossthestationaryconductor.Themotionbetweenthemagneticfieldandtheconducto

5、rmustbeinsuchamannerthatlinesofforcearecutbytheconductor.Iftherelativemotionbetweenthefieldandconductorissuchthatthelinesofforceareparalleltothemotion,thereisnoinducedEMF.Thatistosay,inordertoinducevoltage,mechanicaldisplacementmusttakeplacebetweenamagneticfieldandaco

6、nductor.However,voltagesareinducedinstillanothermannerwheneverthefluxsurroundingaconductorchangesinmagnitude,directionorboth,voltageisinducedintheconductor.Inthiscase,nomechanicalactionofanykindoccurs,theinducedvoltageistheresultofachangeintherelationshipbetweentheflu

7、xandtheconductor.Amagneticfieldrepresentsstoredenergy,andanychangeinthemagneticfieldaroundaconductorcanproduceareactionintheconductor,whichappearsasaninducedvoltage.Unit10ElectromagneticInduction上一页下一页返回Amagneticfieldisalwayspresentaroundaconductorcarryingacurrent.The

8、magneticfieldproducedbythecurrentisatrightanglestothecurrent.Conversely,achangingmagneticfieldisalwaysassociatedwithanEMF,wh