A copper wire is stretched to make it 0.5 % longer. The percentage change in its electrical resistance if its volume remains unchanged is:

Step-by-step solution

Volume, V = A . l In differential form, d V V = d A A + d l l 0 = d A A + d l l ⇒ d A A = - d l l Also resistance of wire is as follows R = ρ l A diffrentiation formula for resistance is as follows d R R = d l l - d A A d R R = d l l - ( - d l l )             d R R = 2 · d l l d R R × 100 = 2 · d l l × 100 d R R % = 2 × 0 . 5 % d R R % = 1 % ∴ % change in R = 2 × 0.5 % = 1 %