The plates of a parallel plate capacitor are 5 mm apart and 2 m² in area. The plates are in vacuum. A potential difference of 10000 Volts is applied across the capacitor. Calculate (a) the capacitance, (b) the charge on each plate, (c) the surface density of charge, (d) the electric field between plates, and (e) the electric displacement between plates.

The charged capacitor in problem is disconnected from the charging voltage and insulated so that the charges on its plates remain constant. A sheet of dielectric 5 mm thick, of dielectric constant 5, is inserted between the plates. Calculate (a) the electric displacement in the dielectric, (b) the electric field in the dielectric, (c) the potential difference across the capacitor, and (d) its capacitance.