Calculate the mass of copper required to draw a wire `5 km` long having resistance of `5 Omega` .The density of copper is `8.9 xx 10^(3) kg m^(-3)` and resistance of copper is `1.7xx 10^(-8) Omega m`

Answer

`756.5 kg`

Explanation

`R = (rhol)/(A) or A = (rhol)/(R ) = ((1.7 xx10^(-8)) xx (5000))/(5)`
`= 1.7 xx 10^(-5)m^(2)`
Mass of copper required,
m = volume `xx` density `= A l xx d`
`= (1.7 xx 10^(-5)) xx 5000 xx (8.9 xx 10^(3)) = 756.5 kg`