# Calculate the resistance of the copper overhead wire suspended to power the tram engine if the wire is 5 km

July 31, 2021 | education

| **Calculate the resistance of the copper overhead wire suspended to power the tram engine if the wire is 5 km long and has a cross-sectional area of 0.65 cm2.**

To calculate the resistance of the taken copper contact wire, we will use the formula: R = ρ * l / S.

Constants and variables: ρ (specific electrical resistance of copper) = 0.017 Ohm * mm2 / m; l is the length of the wire taken (l = 5 km; in SI l = 5 * 10 ^ 3 m); S – cross-sectional area (S = 0.65 cm2 = 0.65 * 10 ^ 2 mm2).

Let’s make a calculation: R = ρ * l / S = 0.017 * 5 * 10 ^ 3 / (0.65 * 10 ^ 2) = 1.31 Ohm.

Answer: The taken copper contact wire has a resistance of 1.31 ohms.

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