〖教学目的〗第一,理解带电粒子初速度方向与匀强磁场方向垂直时,若只受洛伦兹力作用,将做匀速圆周运动。第二,会推导带电粒子在匀强磁场中做匀速圆周运动的半径和周期公式,并会应用其解决相关问题。第三,知道回旋加速器的构造和原理。〖教学重点、难点〗 〗 〖Teaching purpose First, when the direction of the initial velocity of a charged particle is perpendicular to the direction of a uniform magnetic field, if only the Lorentz force acts, a uniform circular motion will be performed. Second, it will derive the radius and periodic formula of the charged particles in a uniform magnetic field to make uniform circular motion, and it will be applied to solve related problems. Third, know the structure and principle of the cyclotron. 〖Educational focus, difficult point〗