For copper, ρ = 8.93 g/cm³ and M = 63.5 g/mol. Assuming one free electron per copper atom, what is the drift velocity of electrons in a copper wire of radius 0.625 mm carrying a current of 3 A?

Question

Quizplus · Accepted Answer

The drift velocity $ v_d $ can be calculated using the formula $ v_d = \frac{I}{nAe} $, where $ I $ is the current, $ n $ is the number density of electrons, $ A $ is the cross-sectional area, and $ e $ is the charge of an electron. First, calculate $ n $ using $ n = \frac{\rho \cdot N_A}{M} $, where $ \rho $ is the density, $ N_A $ is Avogadro's number, and $ M $ is the molar mass. Then, calculate $ A = \pi r^2 $ with $ r = 0.625 \times 10^{-3} $ m. Substituting these into the drift velocity formula gives the correct answer.

For Copper, ρ = 8