Question

Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area 1.0 × 10^–7 m² carrying a current of 1.5 A. Assume the density of conduction electrons to be 9 × 10²⁸ m^–3.

Answer 1

 Flow of current in the conductor due to drift velocity of the free electrons is given by 

I = neAv_d

v_d = l/neA 

= (15/9 x 10²⁸ x 1.6 x 10^-19 x 1.0 x10^-7)

v_d = 1.048 x 10^-3 m/s ≈ 1mm/s