Estimate the average drift speed of conduction electrons in a copper wire of cross sectional area 1 x 10^{-7} m^{2}, carrying a current of 1.5 A.Assume that each copper atom contributes roughly one conduction electron . The no. of copper atoms per cubic metre is 8.5 x 10^{28}.

Drift speed is

v = I/n A e

Where

I = current

n = number of free electrons

A = cross sectional area of the conductor

e = electronic charge

so,

v = 1.5 / (8.5 x 10^{28}x 10^{-7 }x 1.6 x 10^{-19})

= 1.10 x 10^{-3} m/s

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