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Problem 4 - Entrance Test

A wire of length 1 m and cross-sectional area 10^-6 m^2 has a resistance of 10 ohms. What is the resistivity of the material of the wire?

Correct: D

The resistance of the wire is given by R = ρ(L / A), where ρ is the resistivity, L is the length, and A is the cross-sectional area. Rearranging the equation, we get ρ = RA / L = (10 ohms) * (10^-6 m^2) / (1 m) = 10^-5 ohm-m.