[考古] 中原94
11.An electron is launched(發射) with velocity v in a uniform magnetic field B
.the angle x between v and B is 0~90.As a result,the electron follows a
helix(螺旋線),its velocity vector v returning to its initial value in a
time interval of
(A)2pmvsinx/eB (B)2pmv/eB (C)2pm/eB (D)2pmvcosx/eB
題目就有點不懂
請問一下答案和所需的觀念
謝謝
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 218.160.58.50
→
07/05 02:42, , 1F
07/05 02:42, 1F