Question

Given a plate capacitor of a large parallel sheet of area A and a separation d. Now consider the capacitor is charged with a charge Q and –Q on the opposite plates by removing electrons from the top plate and added to the bottom plate. The positive charges on the top plate will be made of voids of electrons, the so called “holes” that carries the positive charges. Each hole has exactly the same fundamental charge e=1.60x10^-19 C as that of electron but being positive. In the model of electronic conduction these holes are treat as real positively freely moving charges with proximately the same mass as that of electrons. Calculate and formulate the following and compare them with each other:

1. What is the electrostatic energy stored in the capacitor, in terms of Q, A, and d.?
2. Calculate the gravitational potential between the top sheet of holes and the bottom sheets of electrons, and express such energy in terms of Q, A, and d. ?
3. Compare the two forms of energy to see which one is larger. ?

Answer 1