An electric bulb of $100\, watt$ is connected to a supply of electricity of $220\, V$. Resistance of the filament is ............. $\Omega$
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(a) $\frac{{{V^2}}}{R} = P\,$ $ \Rightarrow $ $R = \frac{{{V^2}}}{P} = \frac{{220 \times 220}}{{100}} = 484\,\Omega $
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