QJEEM22Ph187f: JEE Main 2022 Physics - Class 12 JEEM22Ph187f Solution: An aluminium wire is stretched to make its length, 0.4% larger. …

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An aluminium wire is stretched to make its length, 0.4% larger. The percentage change in resistance is :

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$R = \frac{ρ l}{A}$

Also volume will remain constant

i.e., Al = constant $\Rightarrow A \propto \frac{1}{l}$

$∴$ $R \propto l^{2}$

$\frac{Δ R}{R} = 2 \frac{Δ l}{l} = 0.8$

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