The resistance of the filament of an electric bulb changes with temperature. If an electric bulb rated ${\rm{220}}\,\,{\rm{volt}}$ and ${\rm{100}}\,\,{\rm{watt}}$ is connected to $\left( {220\,\, \times \,\,.8} \right)\,\,volt$ sources, then the actual power would be

Between $100\,\, \times \,\,0.8\,\,watt$ and $100\,\,watt$

JEE PHYSICS MCQ: CURRENT ELECTRICITY

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The resistance of the filament of an electric bulb changes with temperature. If an electric bulb rated

\mathrm{220}\,\,\mathrm{volt}

and

\mathrm{100}\,\,\mathrm{watt}

is connected to

\left( {220\,\, \times \,\,.8} \right)\,\,volt

sources, then the actual power would be

View answer and explanation

Correct option: D

Between

100\,\, \times \,\,{\left( {0.8} \right)^2}\,\,watt

and

100\,\, \times \,\,0.8\,\,watt

Option D (Between

100 \times {\left( {0.8} \right)^2}\\ watt

and

100 \times 0.8\\ watt

) is correct because the resistance of the bulb decreases with lower voltage, leading to a power consumption between the calculated limits.