Question

If a 0.1 % increase in length due to stretching, the percentage increase in its resistance will be

• A. 0.2 %
• B. 2 %
• C. 1 %
• D. 0.1 %

Answer 1

Answer: (A)

0.2 %

Answer 2

$R \propto l ^ { 2 }$ ⇒ $\frac { \Delta R } { R } = \frac { 2 \Delta l } { l }$ ⇒ $\frac { \Delta R _ { 0 } } { R } \% = 2 \times 0.1 = 0.2 \%$