Question

A charged particle goes undeflected in a region
containing electric and magnetic fields. It is
possible that
(a) E ➝ ||B ➝, v ➝ || E➝
(b) E ➝ is not parallel to B ➝
(c) v ➝ || B ➝ but E➝ is not parallel to B ➝
(d) E ➝|| B ➝ but v ➝ is not parallel to E ➝

Answer 1

Answer:

option (a) and (b) are possible

Explanation:

if E || B, and v is parallel to these two, then force due to B is zero. and the force due to E acts in the same direction as motion, hence just speed increases without deflection or change in direction. hence option (a)

if E and B are not parallel, it is possible that the electric force is balanced by the magnetic force and the deflection is nullified. Hence Option (b)