Question

A conductor wire having $10^{29}$ free electrons $/ m ^{3}$ carries a current of $20 \,A$. If The cross section of the wire is $1\, mm ^{2}$ then the drift velocity of electrons will be $\left(e=1.6 \times 10^{-19} C \right)$

• A. $1.25 \times 10^{-4} ms ^{-1}$
• B. $1.25 \times 10^{-3} ms ^{-1}$
• C. $1.25 \times 10^{-5} ms ^{-1}$
• D. $6.25 \times 10^{-3} ms ^{-1}$

Answer 1

Answer: (B)

$i=n e A V_{d}$
$20=10^{29} \times 1.6 \times 10^{-19} \times 10^{-6} \times V_{d}$
$V_{d}=1.25 \times 10^{-3} m / s$