Capacitors A and B are identical. Capacitor A is charged so it stores 4J of energy and capacitor B is uncharged. The capacitors are then connected in parallel. The total stored energy in the capacitors is now ____.
U = q^2/2C
The Attempt at a Solution
Ok, I'm not sure if this is allowed.. I already know the answer is 2J. My professor gave us an answer key with the problem done out, but I don't understand what is happening. I'm not sure where 2J went. It says 2J of energy were required to move charge from the charged capacitor to the uncharged one.
I know initial potential of A is 4J, and initial potential of B is 0. For final potential, she has U_final = q^2/2C = 1/2*q^2/2C. Where did the second 1/2 come from?
I would really appreciate some clarification.. I'm really confused.