Question

A charged particle moves in a gravity-free space without change in velocity. Which of the following is/are possible?
(a) E = 0, B = 0
(b) E = 0, B ≠ 0
(c) E ≠ 0, B = 0
(d) E ≠ 0, B ≠ 0

Answer 1

The possible actions are (a), (b) and (d).

Explanation:

• In a gravity-free space, a charged particle can move without any velocity change in the below three ways:
• (1) B = 0, E = 0, that is, on the particle, no force is acting and later, with a constant velocity, it moves.
• (2) E = 0, B ≠​ 0. Along the direction of the velocity v, if there is a magnetic field, then the force will be zero. So, there is no acceleration of the particle.
• (3) Due to the magnetic field, if the force due to electric field balancing each other, then on the particle, the net force acting will be zero. Hence, there will be a constant velocity on the particle.