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An AC supply gives 30 V rms and is connected across a 10 \(\Omega\) resistor. The power dissipated in it is

1. 90 W
2. 90 W
3. 45 W
4. 45 W

Correct answer: 90 W

Solution

For a resistor, the average power is \(P = V_{\text{rms}}^2/R\). Substituting \(V_{\text{rms}} = 30\) V and \(R = 10\,\Omega\), we get \(P = 30^2/10 = 90\) W.

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