If the speed of a charged particle is doubled, how will the magnetic force exerted on the particle change?

Question

a) The force does not depend on the speed.

b) The force will be twice as large.

c) The force will be half as large.

d) The force will be four times as large.

e) None of the above.

Answer 1

The magnitude of the magnetic force on a charged particle moving with speed v is F = qvBsin(θ), where q is the charge of the particle and θ is the angle between the vectors B and v. If v → 2v then we have F = 2qvBsin(θ).