适当地设置条件,可以使带电粒子在匀强磁场中的运动轨迹具有某种对称性,或者使粒子运动方式具有周期性,按着这个思路,可以编拟一类“粒子从哪儿出发最后又返回到哪儿”的题目,这类问题可称为运动粒子回归原点问 Properly setting the conditions can make the trajectory of charged particles have a certain symmetry in the uniform magnetic field, or make the particle motion have periodicity. According to this idea, a class of “particles” can be prepared from where and finally. Back to where the topic is, this type of problem can be called the origin of the moving particle