how do i work out the total energy stored in capacitors connected parrellel and series?

Question

3 capacitors of capacitance 15 µF, 30 µF and 35 µF are connected in parrellel to a 100v battery. calculate the total energy stored in the capacitors. calculate how much less energy would be stored if they were accidently connected in series.

Answer 1

Energy = 1/2 * C * V^2

Total capacitance in parallel = 15 + 30 + 35 = 80 uF

Energy = 1/2 * 80e-6 * 100^2 = 0.4 Joules

If they are connected in series, the total capacitance is:
1 / (1/15 + 1/30 + 1/35) = 7.77 uF

1/2 * 7.77e-6 *100^2 = 0.039 Joules

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