QJEEM24Ph04d2: JEE Main 2024 Physics - Class 12 JEEM24Ph04d2 Solution: By what percentage will the illumination of the lamp decrease…

Question

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By what percentage will the illumination of the lamp decrease if the current drops by 20%?

Accepted Answer

$\begin{aligned} P = i^{2} R \\ P_{int} = I_{int}^{2} R \\ P_{final} = {(0.8 I_{int})}^{2} R \end{aligned}$

% change in power $=$

$\frac{P_{final} - P_{int}}{P_{int}} \times 100 = (0.64 - 1) \times 100 = - 36 %$

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