A charged particles enters a magnetic field perpendicular to it. The particle follows a zigzag path and comes out of it. What happens to its velocity and kinetic energy of the particle? Justify your answer.

As the charged particle enters perpendicular to the magneticfield, the force will act perpendicular to the velocity. Thus the particlestarts moving in the circular path. As force and displacement are perpendicularsthe work done will be zero and kinetic energy will not change. But as it movesin circular path direction of momentum will change but the magnitude is unchanged