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A parallel-plate capacitor is connected to a battery and charged until the potential difference across its plates becomes equal to the battery’s emf. What is the ratio of the energy stored in the capacitor to the work done by the battery?

1. 1/2
2. 1
3. 2
4. 1/4

Correct answer: 1/2

Solution

The energy stored in a capacitor is given by the formula U = 1/2 CV², while the work done by the battery is W = CV². Therefore, the ratio of the energy stored in the capacitor to the work done by the battery is U/W = (1/2 CV²) / (CV²) = 1/2.

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