Question

A current of $10 \,A$ is maintained in a conductor of cross-section $1 \,cm ^{2}$. If the number density of free electrons be $9 \times 10^{28} \,m ^{-3}$, the drift velocity of free electrons is

• A. $6.94 \times 10^{-6} \,m / s$
• B. $5.94 \times 10^{-2} \,m / s$
• C. $1.94 \times 10^{-3}\, m / s$
• D. $2.94 \times 10^{-4} \,m / s$

Answer 1

Answer: (A)

$i=n e A V_{d} $
$10=\left(9 \times 10^{28}\right)\left(1.6 \times 10^{-19}\right)\left(10^{-4}\right) V_{D}$
Solving, we get
$V_{D}=6.94 \times 10^{-6} \,m / s$