Question

There is a current of $0.21 \,A$ in a copper wire whose area of cross-section is $10^{-6} m ^{2}$. If the number of free electrons per $m ^{3}$ is $8.4 \times 10^{28}$, then find the drift velocity, $\left(e=1.6 \times 10^{-19} C \right)$

• A. $2 \times 10^{-5} ms ^{-1}$
• B. $1.56 \times 10^{-5} ms ^{-1}$
• C. $1 \times 10^{-5} ms ^{-1}$
• D. $0.64 \times 10^{-5} ms ^{-1}$

Answer 1

Answer: (B)

$ v_{d} =i / n A e=0.21 /\left(8.4 \times 10^{28} \times 10^{-6} \times 1.6 \times 10^{-19}\right) $
$=1.56 \times 10^{-5} ms ^{-1}$