Question

Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area $2.5\times {10}^{-7}{m}^2$ carrying a current of 2.7 A. Assume the density of conduction electrons to be $9\times {10}^{28}{m}^{-3}$

Answer 1

$I=neA{v}_d{v}_d=\frac{I}{neA}$

$I=2.7A$

$e=1.6\times {10}^{-19}CA=2.5\times {10}^{-7}{m}^2$

n = density of conduction electrons

So, $n=9\times {10}^{28}{m}^{-3}$

$v_d=\frac{2.7A}{9\times {10}^{28}{m}^{-3}\times 1.6\times {10}^{-19}C\times 2.5\times {10}^{-7}{m}^2}=7.5\times {10}^{-4}A.m/C=7.5\times {10}^{-4}m/s$