高等电磁波理论 课件 1 麦克斯韦方程

第一章电磁场基本理论

1.1麦克斯韦方程浙江大学信息与电子工程学院《高等电磁波理论》12AndreMarieAmpere(1775-1836)螺旋管的磁场IBB长导线的磁场安培定律（1826年）3MichaelFaraday(1791-1867)BB磁场随时间变化VgenVgenB面积随时间变化VgenNSNS法拉第定律（1831年）4Faraday’slawofinductionThelawofallseaandallland—Nolies,nodeceit,nocorruptionInthislawsocompleteandsogrand!Ourchildrenwillsingitinchorus–“CirculationofvectorcapE,”Yesthey’llsingastheymarchonbeforeus,“Equals

negativedbydtOf

–Magneticfluxthroughasurface,”©2001WalterFoxSmith法拉第定律之歌They’llconcludeaswestrikeuptheband.We’llmarkallourcoinswithourpurpose--“OnMaxwell’sequationswestand!”It’sFaraday’slawofinductionThatallowsustogeneratepow’r.Itgivesvoltageincreaseorreduction--Wecouldsingonandonforanhour!..矢量电场积分=穿过表面磁通量的时间微分赋予“力量”--电压增减5Inside,outside,countthelinestotell–Ifthechargeisinside,therewillbenetfluxaswell.Ifthechargeisoutside,becarefulandyou’llseeThegoingsinandgoingsoutareequalperfectly.Ifyouwishtoknowthefieldprecise,Andthechargeissymmetric,youwillfindthislawisnice–Quponaconstant–eps’lonnaughttheysay–Equals

closedsurfaceintegralofEdotndA.©2001WalterFoxSmith高斯定律（1832）闭合曲面的电通量积分=内部电荷总量

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常系数《高斯定律之歌》“收支”平衡6JamesClerkMaxwell(1831-1879)麦克斯韦-安培定律（1860）平板电容的失效E路径lII曲面S1曲面S2加个位移电流试试7Mr.Ampere’smagical,mystical,wonderfullaw!OfMaxwell’sequations,itisthelongestandstrangestofall!Ontheleftside,hewrotecirculationOfmagneticfield,‘causeitwasneat.Ontherighthandsideofhisequation–Mu-naughtI–hethoughtitwascomplete.Decadeslater,Maxwellsawdisaster,AlthoughhethoughtofAmpereasasaint–InbetweentheplatesofacapacitorTherightside’szero,buttheleftsideain’t!安培定律之歌Tofixthisproblem,headdedtotherightsideDisplacementcurrent,abrandnewquantity!Itstartedmu-naughteps’lon-naughtandendedbyThetimederivativeofphi-sub-E.AndsotoMaxwellthemyst’rywasrevealed–Hesawhowlightcouldmovethroughemptyspace.ThechangingB-fieldmadethechangingE-field,Andvice-a-versa,allattheperfectpace.两位科学家-同一个定理©2001WalterFoxSmith8电磁“相遇”《电场情歌》©2001WalterFoxSmith相遇前电场：始正终负磁场：自我闭合负能量加锁内耗相遇后电变生磁磁变生电互相扶持齐头并进9麦克斯韦方程组JamesClerkMaxwell(1831-1879)积分形式电磁场可以传播光是一种电磁场电子工程拉开序幕10麦克斯韦方程组（微分形式）