Q 12-03-025NEETJEE MainMedium
A copper wire of cross-section $1\ \text{mm}^2$ carries $1.6$ A. If the number density of free electrons is $10^{29}\ \text{m}^{-3}$, the drift speed is ($e = 1.6 \times 10^{-19}$ C)
Answer: (B) $0.1$ mm/s
$v_d = \dfrac{I}{neA} = \dfrac{1.6}{10^{29} \times 1.6 \times 10^{-19} \times 10^{-6}} = 10^{-4}$ m/s $= 0.1$ mm/s.
Solution by Sreeraj P, M.Sc Physics