Force in the electrostatic field. A square conducting plate, b meters on the side, is located over a very large conducting plate, with a dielectric of thickness d and permittivity e between the plates. The plate is connected to a potential Vas shown in Figure 4.81 and a string connects it to a weight P. Neglecting fringing of the electric field, calculate the potential required so that the plate does not move (the weight is balanced by the electrostatic force).
