A copper conductor 130metrrs long hasa resistance of 4.30ohms. If the resistivity of a copper is 1.42*10ohms determine the cross sectional area of the conductor in mmsquared

Answer 1

this would have been easy if you had used the proper units. The resistivity is Ω-m

So, you have

(130m * 14.2Ω-m)/(A m^2) = 4.30Ω
A = 429.3 m^2

That seems unlikely, so I looked up the resistivity of copper, and it is really 1.7*10^-8 Ω-m

Using that, we get
A = 5.139*10^-7 m^2 = 0.513 mm^2, or a diameter of 0.8 mm

That seems quite small, so maybe there are other errors in the question.