1 Electric Force and Electric Field.pptxVIP专享VIP免费原创优质

ElectricChargeandStaticElectricityElectricChargeAllmatterismadeupofatomsAtomscontain1.Protons(+)2.Neutrons(0)3.Electrons(-)WhatisStaticElectricity?Staticelectricityoccurswhenthereisabuildupofelectricchargeonthesurfaceofamaterial.Itiscalledstaticelectricitybecausethechargesdon’tmove.Theelectricityweuseeverydayinvolvesmovingcharges.Whatischarge?Tounderstandchargewehavetolookatthingsonanextremelysmallscale.Wehavetotryandunderstandthingsthatwecan’tevenseewiththemostpowerfulmicroscope.Atoms!TheatomEverythingweseearounduseverydayismadeofatoms.Wecan’tseeindividualatomsbecausetheyaresosmall.Infactthediameterofanatomisabout0.0000000001mIntheairinyourclassroomthereareabout1500000000000000000000000000atoms.Whatisinsidetheatom?Theatomismadeof3sortsofparticles.TheelectronTheprotonTheneutronWecanimagineeachasatinylittleball.InsideanatomTheprotonsandneutronssittogetherinalumpinthemiddlecalledthenucleus.Theelectronsorbitaroundthenucleus,abitliketheplanetsorbitingtheSun.Mostoftheatomisemptyspaceifatomswerethesizeoffootballfields,thenucleuswouldbeagrainofsandinthemiddleandtheelectronswouldbeorbitingaroundtheedge..ChargeTheelectronisnegativelycharged.Theprotonispositivelycharged.Theneutronhasnocharge,itisneutral.ChargeMostthingshavethesamenumberofelectronsandprotonsinthem.Theydon’thaveanyoverallcharge.Ifthisisn’ttrueinterestingthingscanhappen.Howdochargesbehave?Whatdoyouknowaboutmagnets?2northpoleswillrepeleachother,butanorthandasouthputtogetherwillattractoneanother.oppositesattract,likesrepel.Howdochargesbehave?Exactlythesamethinghappenswithcharges.2positivechargesputtogetherwillrepeleachother.Putapositivechargenearanegativechargeandtheywillattracteachother.Achargedobjectmayevenattractaneutralone.WHY?LawofElectricChargesThelawofelectricchargesstatesthatlikechargesrepel,andoppositechargesattract.Protonsarepositivelychargedandelectronsarenegativelycharged,sotheyareattractedtoeachother.Withoutthisattraction,electronswouldnotbeheldinatoms.RecallThis?TheFundamentalForcesThestrongnuclearinteractionisverystrong,butveryshort-ranged.Itactsonlyoverrangesoforder10-13centimetersandisresponsibleforholdingthenucleiofatomstogether.Itisbasicallyattractive,butcanbeeffectivelyrepulsiveinsomecircumstances.Theelectromagneticforcecauseselectricandmagneticeffectssuchastherepulsionbetweenlikeelectricalchargesortheinteractionofbarmagnets.Itislong-ranged,butmuchweakerthanthestrongforce.Itcanbeattractiveorrepulsive,andactsonlybetweenpiecesofmattercarryingelectricalcharge.Theweaknuclearforceisresponsibleforradioactivedecayandneutrinointeractions.Ithasaveryshortrangeand,asitsnameindicates,itisveryweak.Thegravitationalforceisweak,butverylongranged.Furthermore,itisalwaysattractive,andactsbetweenanytwopiecesofmatterintheUniversesincemassisitssource.HowboutThis?TheFundamentalForcesThestrongnuclearinteractionisverystrong,butveryshort-ranged.Itactsonlyoverrangesoforder10-13centimetersandisresponsibleforholdingthenucleiofatomstogether.Itisbasicallyattractive,butcanbeeffectivelyrepulsiveinsomecircumstances.Theelectromagneticforcecauseselectricandmagneticeffectssuchastherepulsionbetweenlikeelectricalchargesortheinteractionofbarmagnets.Itislong-ranged,butmuchweakerthanthestrongforce.Itcanbeattractiveorrepulsive,andactsonlybetweenpiecesofmattercarryi...