JEE Mains · Physics · STD 12 - 3. current electricity
By what percentage will the illumination of the lamp decrease if the current drops by \(20 \%\) ?
- A \(46 \%\)
- B \(26 \%\)
- C \(36 \%\)
- D \(56 \%\)
Answer & Solution
Correct Answer
(C) \(36 \%\)
Step-by-step Solution
Detailed explanation
\(P=i^2 R\) \(P_{\text {int }}=I^2{ }_{\text {int }} R\) \(P_{\text {final }}=\left(0.8 I_{\text {int }}\right)^2 R\) \(\% \text { change in power }=\) \(\frac{P_{\text {final }}-P_{\text {int }}}{P_{\text {int }}} \times 100=(0.64-1) \times 100=-36 \%\)
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