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Question:

Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area 1.0 × 10⁻⁸ m² carrying a current of 1.5 A. Assume the density of conduction electrons to be 9 × 10²⁸ m⁻³.

Solution:

Drift velocity is given by:
vd = J/ne
vd = I/neA
vd = 1.5/(9 × 10²⁸ × 1.6 × 10⁻¹⁹ × 10⁻⁸)
vd = 1.042 × 10⁻⁴ m/s