作者PHONm (埃及的旅程)
看板Physics
标题[题目] 普物两题 电子在随时变磁场的运动
时间Tue Feb 24 17:27:45 2009
[领域] 普物
[来源] 台大考题 (课本习题、考古题、参考书...)
[题目]
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?
[瓶颈]
dB/dt = 0, 则 qvB=mv^2/r >> r = mv/qb 作圆周运动
但 B = Ct+C' (C>0)
所以r会变小，但是 ∫E．ds = - dΦb/dt
则有感应电场，使v变大，请问这边的思考方向错在哪?
感谢
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※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 140.112.125.84
1F：推 xhole:r=mv/qB才对!? 02/24 23:06
2F：→ xhole:(mv)/(qB) 02/24 23:06
3F：→ PHONm:打字打太顺手 谢谢楼上 02/25 09:09
※ 编辑: PHONm 来自: 140.112.125.84 (02/25 21:20)