- #1

RK1992

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a 180 microfarad capacitor is charged so that is has a PD of 100v across the plates. i calculate the energy stored as 0.5cv² = 0.9J

the question then asks me to calculate the work done by the battery in charging the capacitor. the mark scheme says that i should use W = QV = CV² and should therefore get 1.8J

why is the work done in charging the capacitor different to the energy stored on it? i have never heard my teacher mention this fact in lessons, so i seriously have no idea where this has come from.. where does this equation come from? thanks