# physics

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if a 5microfarad capacitor is charged by a 20volts battery and it is then connected across an uncharged 20microfarad capacitor , find the potential energy

• physics -

Find the PE of what?

• physics -

5*10^-6 = Q/20
Q = 10^-4

That charge is distributed on the new capacitance of C = (5+20)10^-6 = 25 *10^-6

V = Q/C
V = 10^-4/(25*10^-6) = 10^2/25 = 4 Volts

Energy = (1/2) Q V = .5 *10^-4 * 4
= 2*10^-4 Joules

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