Calculate the resistivity of copper, a wire of which is 250 meters long

Calculate the resistivity of copper, a wire of which is 250 meters long and has a cross-sectional area of 0.2 mm2 and has a resistance of 40 ohms.

Task data: l (copper wire length) = 250 m; S (cross-sectional area of the wire) = 0.2 mm2; R (the resistance that the copper wire in question has) = 40 ohms.

We express the resistivity of copper from the formula for calculating the resistance: R = ρ * l / S, whence ρ = R * S / l.

Let’s perform the calculation: ρ = 40 * 0.2 / 250 = 0.032 Ohm * mm2 / m.

Answer: According to the calculation, the specific resistance of copper is 0.032 Ohm * mm2 / m.