Q. The resistance of a wire is 'R' ohm. If it is melted and stretched to 'n' times its original length, its new resistance will be :
A) nR
B) $\frac{R}{n}$
C) $n^2R$
D) $\frac{R}{n^2}$
Explanation
[Solution] Volume is constant, so area becomes A/n; $R' = \rho(nl)/(A/n) = n^2R$. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.