Q. If $n,e,\tau$ and $m$ respectively represent the density, charge relaxation time and mass of the electron, then the resistance of a wire of length $l$ and area of cross-section $A$ will be
A) $\frac{ml}{ne^{2}\tau A}$
B) $\frac{m\tau^{2}A}{ne^{2}l}$
C) $\frac{ne^{2}\tau A}{2ml}$
D) $\frac{ne^{2}A}{2m\tau l}$
Explanation
(a) $R = \rho\frac{l}{A} = \frac{m}{ne^{2}\tau}.\frac{l}{A}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.