Question
Answer the following questions:
A charged particle enters an environment of a strong and non-uniform magnetic field varying from point to point both in magnitude and direction, and comes out of it following a complicated trajectory. Would its final speed equal the initial speed if it suffered no collisions with the environment?
Solution
Yes, the final speed would equal the initial speed because, the magnetic force can change the direction of velocity and not its magnitude. The force which is exerted by the magnetic field on the charged particle is always perpendicular to it's motion and hence, does no work.
