Question

If the specific resistance of a wire of length $l$ and radius $r$ is $k$ then resistance is

• A. $k\pi r^2/l$
• B. $\pi r^2/lk$
• C. $kl/\pi r^2$
• D. $k/l{r}^2$

Answer 1

Answer: (C)

$kl/\pi r^2$

Given : Specific resistance $\rho =k$

Cross-section area of the wire $A=\pi r^2$

Resistance of wire is given by $R=\rho \frac{l}{A}=\frac{kl}{\pi r^2}$