Question

 An electron of mass m and cahrge -e is moving through a uniform magnetic field  in vacuum.

At the origin, it has velocity  A screen is mounted perpendicular to the x axis at a distance D from the origin. 

Throughout, you can assume that the effect of gravity is  negligible.

First, suppose Find the y coordinate y of the point at which the electron strikes the screen.

Expross your answer in terms of D and the velocity components  .