Particle circular motion in magnetic field (1 Viewer)

[Octavius]

If a charged particle moves a magnetic field, when it exits the field, why is the magnitude of velocity the same? Is it because of there being no work acting on the particle?

 

[Vall]

You are pretty much correct. When the particle exits the field there is no longer a force acting on the particle (so no work is done on it). If the net force on a body is 0 then (by Newton's second law, F=ma) the acceleration is 0. Thus its velocity remains constant from the point where it exits the magnetic field.