The magnetic force differs from electric force in that:

Question

a) it does not depend on the magnitude of the field

b) it does not depend on the magnitude of the charge

c) it is always opposite to the direction that the field points

d) it is always perpendicular to the direction that the field points

e) None of the above

Answer 1

The force on a charge q in a magnetic field B moving with a velocity v is F = qv x B. This involves the cross product of v and B. The cross product always outputs a vector that is perpendicular to the input vectors. Thus F is perpendicular to both v and B.

The force on a charge q in an electric field E is F = qE. So we see that the magnetic force is always perpendicular to B but the electric force is not perpendicular to E.