1.2交變電磁場ppt課件

1、EJ00sSJ012nSaDDQSdDS12nnSDDnnDD211nSD021BBan0SSdB021nnBB12nnBB021nnBB12nSaHHJSCSdtDJl dH)(12ttSHHJttHH211tSHJ021EEanSCSdtBl dE021ttEEttEE2101tE021EEan12nSaDD12nSaHHJ021BBan0sin()cos()yxEa Ez dtk x0:sin()cos()yxEa Ez dtk x已知H:求0DtBtHJEBD ?tHE0dtEH01EjB 01HEj SEHJ已知 和 ，求?12nSaHHJ12ttSHHJ?01HEj 0001cos

2、()sin()xxjk xjk xxzxzzHaEea jk Eejddd 00200cos()sin()xxjk xjjk xxxzEk Ezzaeaeddd0000cos()cos()2sin()cos()xxxzxEzHatk xddk Ezatk xd00cos()2snyxEJaHatk xd下00cos()2nyxsEJaHatk xd上0000cos()cos()2sin()cos()xxxzxEzHatk xddk Ezatk xd10101,0; 202025 ,20,0. 881( , )60cos(15 105 )20cos(15 105 ) /xE z tetztz V

3、 m82( , )cos(15 1050 )/xEz te Atz V m8818( , )60cos(15 10 )20cos(15 10 ) /80cos(15 10 ) /xxE z tett V met V m82( , )cos(1510)/xEz te At Vm12,ttEE551( , )(6020) /j zj zxE z teeeV m502( , )80/jzxE z teeV mEj BjH1HEj00 xyzxeeeExyzE551(300100)j zj zyEejeje1115580757501(300100)15 1012(2 1010) /3yj zj zj

4、zj zyHEjejejejeeeA m75020410/3jzyHeeA m78107812 10 cos(15 105 )210 cos(15 105 ) /3yHetztz A m7820410 cos(15 1050 ) /3yHez A m78104(0, )10 cos(15 10 ) /3yHtet A m78204(0, )10 cos(15 10 ) /3yHtet A m11,22emwED wHB在時(shí)變場中，電、磁能量相互依存，總能量密度為1122emwwwD EH B 時(shí)變場中，空間各點(diǎn)的電磁能量密度也要隨時(shí)間變化，從而引起能量的流動(dòng)-引入能流密度矢量：S方向：表示能量

5、的流動(dòng)方向大?。簡挝粫r(shí)間穿過與能量流動(dòng)方向垂直的單位面積的能量()()DBEHHEE JEHtt ()1 ()1()22BHH HHHH Btttt()1 ()1()22DEE EEEE Dtttt11()()()22EHHEH BE DE Jt ()()()E HHEEH 11()()22E HH BE DE Jt11()()22sVVE HdsH BE DdVE JdVt SE H方向：表示能量的流動(dòng)方向大?。簡挝粫r(shí)間穿過與能量流動(dòng)方向垂直的單位面積的能量VVSdVEdVHEtSdHE2222121VVSdVEdVHEtSdHE)(2121222RIaEzzaIaHzsurf2aRIaHESzr2220012TavSSdtSdtT1Re*2avSEH1(*)2SEH)()()(avmaveavwwvS)Re(*21HESav*12()EH)( j0e2kztrIHtEzHHrrrzree1abrUErln0000*21|lnln2d)(Re21UIrabUISPbaSHEDHJt DHJt 22EHJJtt 2()HHH 222HHJt 222EJEtt 0B BA()BAEAttt()0AEtAEtAEt1()AAJtt 222()AAJAtt At222AAJt2()AAA 2()()ADAtt 222t222AAJt 0 HJD