# A charged particle moves through a magnetic field perpendicular to its direction. Then (1) kinetic energy changes but the momentum is constant (2) The linear momentum changes but the kinetic energy is constant (3) Both linear momentum and kinetic energy of the particle are not constant (4) Both linear momentum and kinetic energy of the particle are constant

Answer: (2) The linear momentum changes but the kinetic energy is constant

The path of motion of a charge particle approaching a magnetic field in a direction perpendicular to the direction of motion is circular. The direction of velocity changes at every point in circular motion but the magnitude remains constant. As a result, at each point, the tangential momentum will change. Kinetic energy, on the other hand, will remain constant.

Kinetic energy (K.E) = 1/2 MV2

Where

v2 = Square of the velocity magnitude that does not vary.

If the momentu is a mentioned here is angular momentum then both linear momentum and kinetic energy of the particle are constant.