Question

If a copper wire is stretched to make it 0.1 % longer. The percentage change in its resistance is

• A. 0.2 % increase
• B. 0.2% decrease
• C. 0.1 % increase
• D. 0.1 % decrease

Answer 1

Answer: (A)

0.2 % increase

Answer 2

For a given wire, R = with L × s

= volume = V = constant

so that R = ρ = 2 $\frac { \Delta \mathrm { L } } { \mathrm { L } }$ = 2 (0.1 %)
= 0.2 % (increase), Hence correct answer is