Question

7. A 80 uF capacitor in charged by a 50 V battery. The capacitor is disconnected from this
battery and then connected across another uncharged 320 uF capacitor. What is this
electrostatic energy stored by this system.​

Answer 1

Answer:

Once the capacitor is charged and disconnected from the voltage source, the charge is not going anywhere, it will be conserved (ignore the leaking current due to finite resistance of a dielectric since it’s not known from the problem specs). The second cap is a red herring (assuming it had zero charge to begin with). Energy will be lost (there will be sparks when you connect the second cap) but not the charge. It will only distribute between capacitors in proportion to their capacitances but the total charge won’t change.

Q= 50 V * 80 uF = 400 uC

Explanation: