Given,
weight of copper wire = 13.2 kg
Diameter of wire = 4 mm
Radius of wire = \(\frac{4}{2}\) = 2 mm = \(\frac{2}{10}\) = 0.2 cm
Let length of wire = h cm
so,
weight of 1 cubic cm wire = 8.4 gm
= πr2h x 8.4 = 13.2 kg = 13200 gm
= h = \(\frac{13200\times 7}{22\times 0.2\times 0.2\times 8.4}\) = 12500 cm = 125 m