I am having problems with these two questions - Two capacitors are identical, except that one is empty and the other is filled with a dielectric ( = 3.70). The empty capacitor is connected to a 18.0 V battery. What must be the potential difference across the plates of the capacitor filled with a dielectric such that it stores the same amount of electrical energy as the empty capacitor? also.. The plate separation of a charged capacitor is 0.0690 m. A proton and an electron are released from rest at the midpoint between the plates. Ignore the attraction between the two particles, and determine how far the proton has traveled by the time the electron strikes the positive plate. if anyone can help, it would be greatly appreciated.