A parallel plate capacitor, when filled with a dielectric material (x = 3.7) between its plates, has a capacitance of 3.05 pF. The capacitor is initially charged to a certain potential difference AV, after which the voltage source is removed and the capacitor is isolated. (a) Now the dielectric material is removed from the capacitor and the potential difference across the plates is found to be 510 V. Determine the initial potential difference AV, across the plates of the capacitor. (b) Determine the work done in removing the dielectric material. n]