Can an electron at rest in a magnetic field be set into motion by the magnetic field? what if it were at rest in an electric field?

By a magnetic field: no

By an electric field: yes

Explanation:

The force exerted by a magnetic field on an electron is

where

q is the electron charge

v is the speed of the electron

B is the strength of the magnetic field

is the angle between the direction of v and B

As we see from the formula, if the electron is at rest, then v = 0, and therefore the force is also zero: F = 0. Therefore, the magnetic field cannot set the electron into motion.

On the other hand, the force exerted on an electron by an electric field does not depend on the speed:

where E is the intensity of the electric field

Therefore, the electric force acts also when the electron is at rest, so it is able to set the electron into motion.

gas and liquid