Q. An electric wire of length $'L'$ and area of cross-section $a$ has resistance $R\ ohm.$ Another wire of the same material having same length and area of cross-section $4a$ has a resistance of
A) $4R$
B) $R/4$
C) $R/16$
D) $16R$
Explanation
(b) $R = \frac{\rho l}{a}$ for first wire and $R^{'} = \frac{\rho l}{4a} = \frac{R}{4}$ for second wire
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.