Re: [理工] [電磁]平面波

看板Grad-ProbAsk作者big1p (biglp)時間14年前 (2011/11/19 11:15)推噓3(3推 0噓 10→)

留言13則, 4人參與討論串2/3 (看更多)

※ 引述《big1p (biglp)》之銘言： : 1. : _ _ : A uniform plane wave with E = axEx propagates in a lossless simple medium : (εr=4, μr=1, σ=0) in the +z direction. Assume that Ex is sinusoidal with a : -4 : frequency 100 MHz and has a maximum value of 10 (V/m) at t=0 and z=1/8(m). : -8 : Determine the locations where Ex is a positive maximum when t=10 (s). : 2. : The instantaneous expression for the magnetic field intensity of a uniform : plane wave propagating in the +y direction in air is given by : _ _ -6 7 : H = az4*10 cos(10πt-ky+π/4) (A/m) : Determine the locations where Hz vanishes at t=3(ms). : 對這種題目沒什麼概念.. : 煩請各位高手指點一下第一題會了第二題的詳解是 π π π -π k= ---- (rad/s), t=0 時, H=0 => -ky + --- = + --- => ky = --- 30 4 2 4 -λ n 得 y= --- ±---λ, n=0,1,2,3... 之後把λ算出來代進去 8 2 y=-7.5±30n (m), n=1,2,3... 有點看不懂麻煩指點一下謝謝 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 111.249.155.142

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akisora

11/20 00:05, , 1^F

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akisora

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big1p

11/20 09:14, , 3^F

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