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Question:

When 5 V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is 2.5 × 10⁻⁸ m/s. If the electron density in the wire is 8 × 10²⁸ m⁻³, calculate the resistivity of the material of the wire.

Solution:

Resistivity of a material is given by , ρ = V/(vdnel)
Given: V = 5V, L = 0.1m, vd = 2.5 × 10⁻⁸ m/s, n = 8 × 10²⁸ m⁻³
Therefore ρ = 5/(2.5 × 10⁻⁸ × 8 × 10²⁸ × 1.6 × 10⁻¹⁹ × 0.1) = 1.56 × 10⁻⁹ Ωm