Parallel-plate, air-filled capacitor has a charge of 20.0 μC and a gap width of 0.100 mm. The potential difference between the plates is 200 V. (a) What is the electric field between the plates? (b) What is the surface charge density on the positive plate? (c) If the plates are moved closer together while the charge remains constant, how do the electric field, surface charge density, and potential difference change, if at all? Explain your answers