A charged particle moves through a magnetic field perpendicular to its direction. Then

A charged particle moves through a magnetic field perpendicular to its direction. Then
  1. both momentum and kinetic energy of the particle are changed
  2. its momentum changes but its kinetic energy remains constant
  3. its kinetic energy changes but momentum remains constant
  4. both momentum and kinetic energy of the particle remains constant

Solution

Magnetic force is perpendicular to the direction of motion of the particle. Therefore no external work is done and the kinetic energy remains constant. The particle undergoes uniform circular motion, however due to change in direction of motion velocity is not constant. So the momentum is not constant, during uniform circular motion. Therefore, option (B) is correct.

Asked in: MHT CET 2022 (08 Aug Shift 2)

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