Question

At room temperature, copper has free electron density of $8.4 \times {10}^{28}m^{-3}$.
The electron drift velocity in a copper conductor of cross-sectional area of $ {10}^{-6}m^{2}$ and carrying a current of 5.4 A, will be

• A. $4{ms}^{-1}$
• B. $0.4{ms}^{-1}$
• C. $4{cms}^{-1}$
• D. $0.4{mms}^{-1}$

Answer 1

Answer: (D)

Drift velocity in a copper conductor
$V_d=\frac {i}{neA}$= $\frac {5.4}{8.4 \times {10}^{28}\times 1.6 \times {10}^{-19}\times {10}^{-6}}$
$=0.4 \times {10}^{-3}{ms}^{-1}$
$0.4{mms}^{-1}$