Compute all parts of given problem:
Problem: A parallel-plate capacitor with plate area 4.0cm^2 and air-gap separation 0.50 mm is connected to a 9.0-V battery, and fully charged. The battery is then disconnected.
Part A: What is the charge on the capacitor?
Part B: The plates are now pulled to a separation of 0.75 mm. What is the charge on the capacitor now?
Part D: What is the potential difference between the plates now?
Part E: How much work was required to pull the plates to their new separation?
Any help I can get on this problem is greatly appreciated! I'm not too familiar with this problem.