An electron beam, whose kinetic energy is K, comes out of a thin wall "Window" at the accelerator tube end.

An electron beam, whose kinetic energy is K, comes out of a thin wall "Window" at the accelerator tube end. Distance d from

this window is there metal plate, perpendicular to the direction of the outgoing beam. Which should be direction and magnitude of the

magnetic field to be applied to prevent the beam to hit the plate? ( suppose that e and me are known ).