The number density of free electrons in copper is nearly 8 × 10 28 m - 3 . A copper wire has its area of cross-section = 2 × 10 - 6 m 2 and is carrying a current of 3 . 2 A . The drift speed of the el

Question

The number density of free electrons in copper is nearly 8 × 10 28 m - 3 . A copper wire has its area of cross-section = 2 × 10 - 6 m 2 and is carrying a current of 3 . 2 A . The drift speed of the electrons is _____ × 10 - 6 m s - 1 .

TestHub · Accepted Answer

The formula to calculate the current through any conductor is given by
$I = n A e v_{d} . . . (1)$
Substitute the values of the given parameters into equation (1) and solve to calculate the required drift velocity of the electrons.
$\begin{array}{rcl} 3.2 & = & 8 \times 10^{28} \times 2 \times 10^{- 6} \times 1.6 \times 10^{- 19} \times v_{d} \\ \Rightarrow & v_{d} = \frac{3.2}{16 \times 1.6 \times 1000} m s^{- 1} \\ = & 125 \times 10^{- 6} m s^{- 1} \end{array}$

Physics - Current Electricity Question with Solution | TestHub

Doubts & Discussion