Q. If a wire is stretched to make it 0.1% longer, its resistance will
A) Increase by 0.2%
B) Decrease by 0.2%
C) Decrease 0.05%
D) Increase by 0.05%
Explanation
(a) $R = \frac{Sl}{A} = \frac{Sl^{2}}{V}$
$\therefore\ \ \ \frac{\mathrm{\Delta}R}{R} = 2\frac{\mathrm{\Delta}l}{l} = + 2.0\%$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.