A wire of $1 \Omega$ has a length of 1 m . It is stretched till its length increases by $25 \%$. The

Question

A wire of $1 \Omega$ has a length of 1 m . It is stretched till its length increases by $25 \%$. The percentage change in resistance to the nearest integer is

Professor PC Thomas Classes · Answer

Volume is constant. $R \propto l^2$. If $l \rightarrow 1.25l$, $R \rightarrow 1.5625R$. Change is $\approx 56\%$.