Alright, here's the problem. You're told that there are two square metal plates with side length L and a distance d away from each other. One has charge +Q, the other -Q. Then they ask for the magnitude for the charge between the plates, not close to the edge. Here's what I have so far: The electric field between them obviously isn't 0. I've got sigma = (magnitude of charge)/area. The electric field for one plate is E = sigma/(2 * epsilon). Since the fields from both plates in between them point in the same direction, the total field would be E = sigma/epsilon. This was going great until I realized the I still had an unused variable, distance d. I have no idea of what to do with it. I tried multiplying E by d, then dividing it by d, but I don't like the way those numbers look. Please help!