Question

A copper wire with a cross-section area of $2\times 10^{-6}{m}^2$ has a free electron density equal to $5\times 10^{22}/c{m}^{-3}$. If this wire carries a current of $16A$, the drift velocity of the electron is

• A. 1 m/s
• B. 0.1 m/s
• C. 0.01 m/s
• D. 0.001 m/s
• E. 0.0001 m/s

Answer 1

Answer: (D)

Drift velocity, $V_d=\frac{I}{neA}$
Given, $=n=5\times 10^{22}/c{m}^3$
$=5\times 10^{22}\times 10^6/m^3$
$e=1.6\times 10^{-19}C$
$A=2\times 10^6{m}^2$
$I=16A$
$V_d=\frac{16}{5\times 10^{28}\times 1.6\times 10^{-19}\times 2\times 10^{-6}}$
$=\frac{1}{10^3}=0.001m/s$