Question

( 13. An electron performs circular motion of radius r, perpendicular to a uniform
magnetic field B. The kinetic energy gained by this electron in half the revolution
(A) = 1/2mv2
(B) - 1/4mv2
(C) zero
(D) πηΒeν​

Answer 1

Answer: zero

Explanation:

Here only v is perpendicular to B..

Electron undergoes circular motion without change in magnitude of velocity.. Only direction of velocity changes.. Therefore gain in KE is zero