Question

If a copper wire is stretched to make it 0.1% longer, the percentage increase in resistance will be

• A. 0.2
• B. 2
• C. 1
• D. 0.1

Answer 1

Answer: (A)

0.2

Answer 2

In case of streching R ∝ l² So $\frac{\Delta R}{R} = 2\frac{\Delta l}{l} = 2 \times 0.1 = 0.2$