(Solved): Electrons are emitted at A with a velocity u at the angle into the space between two charged pla ...

Electrons are emitted at $A$ with a velocity $u$ at the angle $?$ into the space between two charged plates. The electric field between the plates is in the direction $E$ and repels the electrons approaching the upper plate. The field produces an acceleration of the electrons in the $E$-direction of $eE/m$, where $e$ is the electron charge and $m$ is its mass. Determine the field strength $E$ which will permit the electrons to cross one-half of the gap between the plates. Also find the distance $s$.