A 3.96 μF capacitor and a 7.94 μF capacitor are connected in series across a 14.0 V battery. What voltage would be required to charge a parallel combination of the same two capacitors to the same total energy?
The energy stored in a capacitor is:
Which can also be written in the forms:
The capacitance of the parallel case can be calculated as:
And the capacitance of the series case can be calculated as:
So we want to find a series energy
I'll leave it as an exercise for the student to plug in the numbers required for this calculation.