Question

A beam of electrons moving in a CRO towards the screen gets eleflected by a strong bar magnet because

Answer 1

F***in magnets, how do they work?

Answer 2

Because moving charges feel a force due to the magnetic field.

Answer 3

If the magnetic field is given by B and the charge of an electron is q and v is the velocity of the electron, then the force acting on it is given by:
\[F = q(v \times B)\]
where F, v and B are vectors.