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# What is the resistance of a 5.00km long copper wire that has a diameter of 0.500cm?

resistivity of copper: 1.68x10^-8 ohm meters

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- billrussell42Lv 71 month agoFavourite answer
radius = 0.25 cm = 0.0025 m

area = πr² = 0.00001964 m²

R = (1.68e-8)(5000)/(0.00001964) = 4.28 Ω

Resistance of a wire in Ω

R = ρL/A

ρ is resistivity of the material in Ω-m

L is length in meters

A is cross-sectional area in m²

A = πr², r is radius of wire in m

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