Question

A particle of specific charge (q/m) is projected from the origin of coordinates with initial velocity [u i - v j]. Uniform electric magnetic fields exist in the region along the +y direction, of magnitude E and B. The particle will definitely return to the origin once if

(A) [vB/2πE] is an integer

(B) (u² + v² )^1/2 [B/πE] is an integer

(C) [vB/πE] in an integer

(D) [uB/πE] is an integer

Answer 1

Correct option: (C) [vB/πE] in an integer

Explanation:

For origin, x = 0, and y = 0

For returning at the origin,