Problem: A parallel-plate capacitor has square plates that are 9.00cm on each side and 3.30mm apart. The space between the plates is completely filled with two square slabs of dielectric, each 9.00cm on a side and 1.65mm thick. One slab is Pyrex glass and the other is polystyrene.
Part A: If the potential difference between the plates is 75.0V, how much electrical energy is stored in the capacitor?
I want help to find how much electrical energy is stored in the capacitor and express your answer with the appropriate units.