The length of a metallic wire is increased by $20 \%$ and its area of cross section is reduced by $4 \%$. The percentage change in resistance of the metallic wire is $.......$
JEE MAIN 2023, Medium
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$R =\rho \frac{\ell}{ A }$ be the initial resistance new resistance
$R ^{\prime}=\rho \frac{1.2 \ell}{0.96 A }=1.25 \rho \frac{\ell}{ A }=1.25 R$
$\text { percentage change }=\frac{1.25 R - R }{ R } \times 100=25 \%$
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