# Force acting on a charge between parallel plates

When a charge (say positive) is placed between an upper positively charged plate and a negatively charged plate, it should experience a repulsive force from the top plate and an attractive force to the bottom plate, should it not? Then if I were to calculate the net electrostatic force on that charge, wouldn’t I have to double the magnitude of the force between the charge and one of the plates, since it is experiencing two forces? Why is this not the case?

• "Why is this not the case?" But it is the case. The $E$-field between a pair of oppositely charged plates is twice that of a single charged plate. See here. – lemon Jul 8 '15 at 16:50
• The field (in V/m) across the gap will be the potential difference divided by the gap. It one plate is at 4MV and the other is at ground, a + charge released at the top plate will acquire 4MeV of energy crossing the gap. If the top plate is at 2MV and the bottom plate is at -2MV (relative to a common ground), the + charge will still only acquire 4MeV of energy crossing the gap. – Jon Custer Jul 8 '15 at 18:05