Physics | VITEEE 2018 | Discussion Page

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The resistance of a wire is 'R' ohm. If it is melted and stretched to 'n' times its original length. its new resistance will be

$\frac{R}{n}$

$n^{2}R$

$\frac{R}{n^{2}}$

D) nR

Option B

we know that, R = $\frac{\rho l}{A}$

or R = $\frac{\rho l^{2}}{Volume}$ → $R\propto l^{2}$

According to question $l_{2}= nl_{1}$

$\frac{R_{2}}{R_{1}} = \frac{n^{2}l_1^2}{l_1^2}$

or $\frac{R_{2}}{R_{1}} = n^{2}$

$R_{2}= n^{2}R_{1}$

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