Q. A straight conductor of uniform cross-section carries a current $i$, If $s$ is the specific charge of an electron, the momentum of all the free electrons per unit length of the conductor, due to their drift velocity only is
A) $is$
B) $\sqrt{i/s}$
C) $i/s$
D) $\left( \frac{i}{s} \right)^{2}$
Explanation
(c) $i = nAev_{d}$
or $v_{d} = \frac{i}{nAe}$
Total number of free electrons in the unit length of conductor, $N = nA \times 1.$
Total linear momentum of all free electrons per unit length
$= (Nm)v_{d} = nAm \times \frac{i}{nAe} = \frac{i}{(e/m)} = \frac{i}{s}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.