If E and B are the magnitudes of electric and magnetic field respectively in some region of space, then the possibilities for which a charged particle may move in that space with a uniform velocity of magnitude v are

Options

A. E= vB
B. `E ne 0, B= 0`
C. `E=0, B ne 0`
D. `E ne 0, B ne 0`

Answer

A, C, D

Explanation

Option (a): E= 0 so no electrostatic force. `B ne 0`, but if `vec(B)` is parallel or antiparallel to `vec(v)`, then magnetic force is also zero. Option (b) : Electric field will apply force so velocity will change in this case.
Option (c ): Force due to electric field and magnetic field can balance each other. `q vec(E )+ q(vec(v) xx vec(B))= 0`
Option (d): Both the fields are absent so there is no force.