Question

The length of a wire is doubled by pulling it.
Find the new resistance.
​

Answer 1

resistance remain same.

Answer 2

let The Resistance of wire be R

Its Ressistivity S

Its length and area l and A

$R = \frac{Sl}{A} \\ \\ R = \frac{S {l}^{2} }{A \times l} \\ \\ R = \frac{S {l}^{2} }{v} \\ \\ R ^{1} = \frac{S {(2l)}^{2} }{v} \\ \\ R {}^{1} 4 \frac{S {l}^{2} }v \\ \\ R {}^{1} =4 R \\ \\ here \: v \: is \: volume \: of \: the \: wire \: \\ which \: is \: constant$

hope it helps.