How is voltage between two plates, like in a battery, determined? When you have a 5V battery, is that the potential difference between a point on the positive plate and a point directly across from it on the negative plate? If so, that means they have to be parallel in order for the calculated voltage to be same at any point you choose. Or is the 5V some sort of integration of a bunch of point to point potential differences across the area of the plate? My guess would be the latter for this reason: if the plates were not parallel, then every potential difference between two points will be different because some pairs of points are further away from each other than others. But if you connected a wire, you would still measure a single voltage produced by the two non parallel plates. Any help?