1. A parallel plate capacitor has 20 plates, each 50 mm by 35 mm, separated by a dielectric 0.4 mm thick. If the capacitance is 1000 pF determine the relative permittivity of the dielectric.
2. Calculate the number of plates used in a 0.5 nF capacitor if each plate is 40 mm square, separated by dielectric of relative permittivity 6 and thickness 0.102 mm.