Question

If the electric field inside a capacitor exceeds the dielectric strength of the dielectric between its plates, the dielectric will break down, discharging and ruining the capacitor. Thus, the dielectric strength is the maximum magnitude that the electric field can have without break-down occurring. The dielectric strength of air is 3.0 x 106 V/m, and that of neoprene rubber is 1.2 x 107 V/m. A certain air-gap, parallel-plate capacitor can store no more than 0.046 J of electrical energy before breaking down. How much energy can this capacitor store without breaking down after the gap between its plates is filled with neoprene rubber? Take the dielectric constant of air to be 1.0, and of neoprene rubber to be 6.7.