Unit 4 Revision - moving charged particle in magnetic field

Can you remember how to explain why a moving charged particle moves in a circular path in a magnetic field and why the speed of the particle is constant? Post replies

In a magnetic field a moving charged particle feels a force. The force is always perpendicular to the velocity therefore the particle moves in a circular path. The velocity must be changing as the particle is changing direction but speed is a scalar quantity so the speed remains constant.

Thanks for that Sophie - great explanation of why a moving charged particle travels on circular path in a magnetic field. Does anyone know what further details are needed to explain why the speed of the particle does not change? You need to talk about work done.

There is no work done on the particle because the force always acts at right angles to the velocity of the particle so the speed reamains constant.

Well done - this is now a full answer - no work is done on the particle in the direction in which it is travelling. therefore there is no change in kinetic energy and no change in speed.