带电粒子在匀强磁场中作圆周运动的问题是近几年高考的热点,这些题不但涉及洛伦兹力,而且往往与几何关系相联系,使问题难度加大,但无论这类题多么复杂,其关键一点在于画轨迹,只要确定了轨迹,问题便迎刃而解,下面列举几种确定带电粒子运动轨迹的方法.一、对称法带电粒子如果从一直线边界进入又从该边界射出,则其轨迹关于入射点和出射点线段的中垂线对称,入射速度方向与出射速度方向 The problem of circular motion of charged particles in a uniform magnetic field is a hot spot in college entrance examination in recent years. These questions not only relate to Lorentz force, but also relate to the geometric relations to make the problem more difficult, however no matter how complex , The key point is to draw the trajectory, as long as the trajectory determined, the problem will be solved, the following list of several methods to determine the trajectory of charged particles.First, the symmetry method If the charged particles from a straight line into the boundary and from the border, the trajectory With respect to the perpendicular bisector of the line segment between the incident point and the outgoing point, the direction of the incident velocity and the direction of the outgoing velocity