题：在场强为 BO的匀强磁场中，质量为 m、带电量为 q的粒子以 vO的速率做匀速圆周运动，其轨道半径为 RO。若磁场突然增强，带电粒子的速率及轨道半径将如何变化 ?　　原解：如图一所示，因为带电粒子在磁场中运动时，洛仑兹力对电荷不做功，所以在磁场增强时，虽洛仑兹力变大 Problem: In a uniform magnetic field with a field strength of BO, particles of mass m and charge q make a uniform circular motion at the velocity of vO, with an orbit radius of RO. If the magnetic field suddenly increases, how will the charged particle’s velocity and orbital radius change? The original solution: As shown in Figure 1, when the charged particle moves in a magnetic field, the Lorentz force does not work on the charge, so when the magnetic field is enhanced, Lorentz force becomes larger