Problem 6 (20 points) A plane-parallel capacitor of the plate area A = 100 cm and the distance between plates b = 1 mm initially has a glass slab inserted into it (Er = 6.5). The capacitor is charged by putting the charge Q = 10-10 C into its plates and is disconnected from the voltage sources after this. How much energy does it take to remove the glass slab from the capacitor