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Question:

A current of 5A passes through a copper conductor (resistivity = 1.7 × 10⁻⁸ Ωm) of radius of cross-section 5mm. Find the mobility of the charges if their drift velocity is 1.1 × 10⁻³ m/s.

1.3m²/Vs

1.5m²/Vs

1.8m²/Vs

1.0m²/Vs

Solution:

The correct option is D 1.0m²/Vs
μ = Vd/E = ρJ = (1.1 × 10⁻³)/(1.7 × 10⁻⁸ × 5/(π × 25 × 10⁻⁶)) = (1.1 × 10⁻³ × π × 25 × 10⁻⁶)/(1.7 × 10⁻⁸ × 5) ≈ 1.01m²/Vs