A 120-m long copper wire (resistivity 1.68 × 10^-⁸ Ω∙m) has resistance 6.0 Ω. What is the diameter of the wire?

Question

Quizplus · Accepted Answer

The resistance R of a wire is given by R = ρL/A, where ρ is resistivity, L is length, and A is cross-sectional area. Solving for A gives A = ρL/R. The area A of a circle is π(d/2)^2, where d is the diameter. Solving for d gives d = 2√(A/π). Substituting the given values, we find d ≈ 0.65 mm.

A 120-M Long Copper Wire (Resistivity 1