Potential Energy of an electron in a parallel plate capacitor

[Seydlitz]

Homework Statement

What is the potential energy of an electron in a parallel plate capacitor if kept on the negative plate before being released?

Homework Equations

1/2mv^2 = qV = PE
Capacitor Energy = 1/2QV

The Attempt at a Solution

1/2mv^2 = qV = PE

However if I'm not mistaken there's also 1/2QV equation that states the energy stored in a capacitor? Which one then should I choose for this electron problem? The normal qV or the 1/2qV?

 

[Delphi51]

The force on the electron due to the E field of the capacitor is F = qE = eV/d.
As it falls the distance between plates, the work done by this force is W = F*d = eV.
So your have it right. The 1/2QV must for something else, perhaps the electrical energy stored in the capacitor.