Question

Calculate the resistance of 1 km long copper wire of radius 1 mm.
(Resistivity of copper =1.72 × 10-8 Ω m

Answer 1

Hey!

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Length = 1km
= 1000 m

Radius = 1mm
= 1 × 10^-³

Resistivity of copper = 1.72 × 10^-8 Ω m

Resistance = Resistivity of copper × Length / Area

R = rho × L/A

R = rho × L / πr²

R = 1.72 × 10^-8 × 1000 / ( 22/7 × 1 × 10^-3)²

R = 5.5 ohm


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Hope it helps...!!!

Answer 2

Thanks for your question !

Length of copper wire (l) = 1 km (1000 m.)

Radius of the copper wire (r) = 1 mm (1 x 10^ -3 m)

Resistivity of the copper (p) = 1.72 x 1 0-8 W m

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Now,

Area of cross section = π × r²

= 3.14 x 10^-3 x 10^-3

= 3.14 x 10^-6

R = pl / A

= (1.72 x 1 0-8 x 1000 ) / 3.14 x 10^-6

= 5.5 ohm