Question

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. $(i / s)^{2}$

Answer 1

Answer: (C)

$i=n Aev _{ d }$
Or $v_{d}=\frac{i}{n A e }$
Total number of free electrons in the unit length of conductor,
$N=n A \times 1$
Total linear momentum of all the free electrons per unit length
$=( Nm ) v _{d}= nAm \times \frac{i}{ nAe }=\frac{i}{(e/m)} =\frac{i}{s}$