高等電磁波理論 課件 1 麥克斯韋方程

第一章電磁場基本理論

1.1麥克斯韋方程浙江大學(xué)信息與電子工程學(xué)院《高等電磁波理論》12AndreMarieAmpere(1775-1836)螺旋管的磁場IBB長導(dǎo)線的磁場安培定律（1826年）3MichaelFaraday(1791-1867)BB磁場隨時間變化VgenVgenB面積隨時間變化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!..矢量電場積分=穿過表面磁通量的時間微分賦予“力量”--電壓增減5Inside,outside,countthelinestotell–Ifthechargeisinside,therewillbenetfluxaswell.Ifthechargeisoutside,becarefulandyou’llseeThegoingsinandgoingsoutareequalperfectly.Ifyouwishtoknowthefieldprecise,Andthechargeissymmetric,youwillfindthislawisnice–Quponaconstant–eps’lonnaughttheysay–Equals

closedsurfaceintegralofEdotndA.?2001WalterFoxSmith高斯定律（1832）閉合曲面的電通量積分=內(nèi)部電荷總量

×

常系數(shù)《高斯定律之歌》“收支”平衡6JamesClerkMaxwell(1831-1879)麥克斯韋-安培定律（1860）平板電容的失效E路徑lII曲面S1曲面S2加個位移電流試試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.兩位科學(xué)家-同一個定理?2001WalterFoxSmith8電磁“相遇”《電場情歌》?2001WalterFoxSmith相遇前電場：始正終負(fù)磁場：自我閉合負(fù)能量加鎖內(nèi)耗相遇后電變生磁磁變生電互相扶持齊頭并進9麥克斯韋方程組JamesClerkMaxwell(1831-1879)積分形式電磁場可以傳播光是一種電磁場電子工程拉開序幕10麥克斯韋方程組（微分形式）