A charge q moving along the X-axis with a velocity is subjected to a uniform magnetic field acting along the Z-axis.as it crosses the origin O.

(a) Trace its trajectory.
(b) Does the charge gain kinetic energy as it enters the magnetic field? Justify your answer.

Explanation

(a)
(b) Here, the force acting on the charge particle changes the direction only. Hence, the kinetic energy will remain same.