a) A parallel-plate air capacitor of area A = 11.5 cm2 and plate separation of d = 2.80 mm is charged by a battery to a voltage of 63.0 V. What is the charge on the capacitor?
b) If a dielectric material with ? = 3.80 is inserted so that it fills the volume between the plates (with the capacitor still connected to the battery), how much additional charge will flow from the battery onto the positive plate?