A wire of resistance $R_{1}$ is drawn out so that its length is increased by twice of its original length.The ratio of new resistance to original resistance is.
JEE MAIN 2022, Easy
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$R _{1}=\rho \frac{ L _{1}}{ A _{1}}$
$R _{2}=\rho\left(\frac{3 L _{1}}{ A _{1} / 3}\right)=9 \rho \frac{ L _{1}}{ A _{1}}$
$\therefore \frac{ R _{2}}{R _{1} }=9$
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