《物理电学》英文版教学课件Torque On A Current Loop In A Uniform.ppt

Withtheknowledgethataforceisexertedonacurrent-icfield,(dsXB=0forthesesides).Themagnitudeoftheforcesonthesidesoflengthaisgivenby:F2=F4=I·a·BThedirectionofF2isoutofthepage;,andweassumethattheloopispivotedsothatitcanrotateaboutpointO,,whichismaximuminthisposition,is:Tmax=I·a·b·B:TheareaoftheloopA=a·b;Tmax=I·A·BIfthecurrentdirectionwerereversed,(thedashedline).,’:r=b/2F=F2·sinT=F2·sin·b/2NettorqueaboutpointO:T=2·F2·sin·b/2T=F2·b·sinRemember:F2=I·a·BT=I·a·B·b·sinT=I·A·B·sinThetorquehasamaximumvalueI·A·icfieldisparalleltotheplaneoftheloop(angleqbetweenAandB=90°).Thetorqueis0N·icfieldisperpendiculartotheplaneoftheloop(angleqbetweenAandB=0°=180°).Thelooptendstorotatetosmallervaluesofq(icfieldvectorB).