We have,
Weight of copper wire = 13.2 kg = 13200 gm
Diameter of wire = 4 mm
Radius of wire = d/2 = 4/2 = 2mm = 0.2cm
Let length of wire be ‘h’ cm
So,
Weight (Density) of 1 cubic cm wire = 8.4 gm
We know, volume = weight/density
Volume × density = weight
πr2h × 8.4 = 13200
22/7 × 0.2 × 0.2 × h × 8.4 = 13200
h = 13200×7 / 22×0.2×0.2×8.4
= 92400/7.392
= 12500 cm = 125m
∴ Length of 13.2kg of copper wire is 125 m.
