Question

calculate the mass of copper required to draw a wire 5 km long having resistance oh 5 ohm. the density of copper is 8900 kg/meter cube and resistivity of copper is 1.7*10^-3

Answer 1

R=ßl/a
Where R is Resistance, ß is resistivity l is length, a is area.
Substituting the values.
5=1.7×10-³×5×10³/a
a= 1.7 m³
Density =m/volume
M=density ×vol

Vol=area×length
=1.7×5×10³= 8.5×10³m³

Mass= 8900×8.5×10³
= 7.565×10^7 kg