A charged particle with charge q enters a region of constant, uniform and mutually orthogonal fields `vec E` and `vec B` with a velocity perpendicular to both `vec E " and " vec B` , and comes out without any change in magnitude or direction of `vec v`. Then

Options

A. ` vec v = vec B xx vec E // E^2`
B. `vec v = vec E xx vec B // B^2`
C. `vec v = vec B xx vec E // B^2`
D. `vec v = vec E xx vec B // E^2`

Answer

B