A particle moves in a region having a uniform magnetic field and a parallel, uniform electric field. At some instant, the velocity of the particle is perpendicular to the field directjion. The path of the particle will be

Options

A. a straight line
B. a circle
C. a helix with uniform pitch
D. a helix with non-uniform pitch

Answer

D

Explanation

Due to magnetic field, particle moves in a circle.
Due to electric field, particle moves along electric field with increasing speed, hence path will be helical with non-uniform pitch.