美国物理教科书20.pdf

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1、540-545CH20-S1-8458133/22/042:29AMPage540WhatYou’llLearn•Youwillobservethebehaviorofelectricchargesandanalyzehowthesechargesinteractwithmatter.•Youwillexaminetheforcesthatactbetweenelectriccharges.WhyIt’sImportantStaticelectricityenablestheoperationofdevic

2、essuchasprintersandcopiers,butithasharmfuleffectsonelectroniccomponentsandintheformoflightning.LightningThetinysparkthatyouexperiencewhenyoutouchadoorknobandthedazzlingdisplayoflightninginastormarebothexamplesofthedischargeofstaticelectricity.Thechargingpr

3、ocessesandthemeansofdischargingarevastlydifferentinscale,buttheyaresimilarintheirfundamentalnature.ThinkAboutThis
Whatcauseschargetobuildupinathundercloud,andhowdoesitdischargeintheformofaspectacularlightningbolt?physicspp.com540KentWood/PhotoResearchers54

4、0-545CH20-S1-8458136/7/047:43AMPage541Whichforcesactoveradistance?QuestionWhathappenswhenaplasticrulerisrubbedwithwoolandthenbroughtnearapileofpaperscraps?ProcedureCriticalThinking1.Place15-20scrapsofpaperfromaholeWhatforcesareactingonthepiecesofpaperpunch

5、onthetable.beforetherulerisbroughtclosetothem?Whatcanyouinferabouttheforcesonthepaper2.Takeaplasticrulerandrubitwithapieceaftertherulerisbroughtnear?ofwool.3.Bringtherulerclosetothepiecesofpaper.BasedonyouranswerstothepreviousObservetheeffecttherulerhasont

6、hescrapsquestions,formahypothesisthatexplainstheofpaper.effecttherulerhasonthescrapsofpaper.AnalysisWhathappenstothepiecesofpaperwhentherulerisbroughtclosetothem?Whathappenstothepiecesofpaperthatcomeincontactwiththeruler?Didyouobserveanyunexpectedresultswh

7、entherulerwasbroughtclosetothepaperscraps?Ifso,describetheseresults.20.1ElectricChargeoumayhavehadtheexperienceofrubbingyourshoesonacarpetto
ObjectivesYcreateasparkwhenyoutouchedsomeone.In1752,Benjamin•DemonstratethatchargedFranklinsetoffaflurryofresearchi

8、nthefieldofelectricitywhenhisobjectsexertforces,bothfamouskiteexperimentshowedthatlightningissimilartothesparksattractiveandrepulsive.causedbyfriction.Inhisexperiment,Franklinflewakitewithakey•Recognizethatch