中学生物理讨论区

kensai

XiaoFish99 发表于 16-7-2016 01:08 AM
谁能向我解释为何答案是B吗。
Need use fleming left hand rule?
求大大指导，感激不尽！

F=q V (x) B =qVB sin(theta)

q=Charge
v= velocity of electron
B= magnetic field
(x) cross vector

v 和 B 是 collinear, 所以theta = 0, F=0
electron beam is not affected.