Question

Explain in terms of force and displacement, why magnetic field cannot do any work?

Answer 1

The Lorentz force is defined as .... F=q (v×B) , where is q = charge, F = magnetic force, B= Magentic field, v = velocity of charge carriers.

The magnetic force is always normal to the velocity and thus is always normal to the path of displacement.

Again, the workdone by magentic field is defined as the dot product of magnetic Force and displacement...

dW = F.dS, where S = displacement.

Since the force and displacement are perpendicular to each other, THe net work done by magnetic field is Zero.