作者PHONm (埃及的旅程)
看板Physics
標題[題目] 普物兩題 電子在隨時變磁場的運動
時間Tue Feb 24 17:27:45 2009
[領域] 普物
[來源] 台大考題 (課本習題、考古題、參考書...)
[題目]
A particle of charge q and mass m is moving on xy-plane. There is uniform
magnetic field B akong Z-direction. Now the magnetic feild increases steadily,
i.e. dB/dt = C. How will this affect the motion of the particle initially?
will the cyclotron radius increase or decrease? why?
[瓶頸]
dB/dt = 0, 則 qvB=mv^2/r >> r = mv/qb 作圓周運動
但 B = Ct+C' (C>0)
所以r會變小，但是 ∫E．ds = - dΦb/dt
則有感應電場，使v變大，請問這邊的思考方向錯在哪?
感謝
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◆ From: 140.112.125.84
1F：推 xhole:r=mv/qB才對!? 02/24 23:06
2F：→ xhole:(mv)/(qB) 02/24 23:06
3F：→ PHONm:打字打太順手 謝謝樓上 02/25 09:09
※ 編輯: PHONm 來自: 140.112.125.84 (02/25 21:20)