Question

At room temperature, copper has free electron density of 8.4 × 10²⁸ per m³. The copper conductor has a cross-section of l0⁻⁶ m² and carries a current of 5.4 A. The electron drift velocity in copper is:

Options

• 400 m/s

• 0.4 m/s

• 0.4 mm/s

• 72 m/s

Answer 1

0.4 mm/s

Explanation:

v_d = `"I"/"neA"` Here, i = 5.4 A, n = 8.4 × 10²⁸ per m³

A = 10⁻⁶ m², e = 1.6 × 10⁻¹⁹ C

∴ v_d = `5.4/(8.4 xx 10^28 xx 1.6 xx 10^-19 xx 10^-6)`

= 0.4 mm/s