Question

If a copper wire is stretched to increase its length by $20 \%$ The percentage increase in resistance of the wire is _______$\%$

Answer 1

The correct answer is 44.
As volume is constant,
So resistance ∝ (length )2
⇒% change in resistance

$\frac{1.44 R_0}{R_0}×100=0.44×100$

$=44\%$