Question

A charged particle in a plasma trapped in a magnetic bottle leaks out after a millisecond. What is the total work done by the magnetic field during the time the particle is trapped?

(a) Maximum

(b) Minimum

(c) Zero

(d) Depends on the strength of the magnetic field

I have been asked this question in examination.

The query is from Motion in a Magnetic Field topic in chapter Moving Charges and Magnetism of Physics – Class 12

Answer 1

Correct choice is (c) Zero

To explain I would say: Work done is zero. Since a magnetic field exerts a force perpendicular to the direction of motion of the charged particle, no work is done by it on the charged particle. Therefore, the total work done by the magnetic field during the time the particle is trapped is zero.