a copper wire 3mm in diameter ,is wound about a cylinder whose length is 12cm , and diameter 10cm so as to cover the csa of the cylinder . find the length and mass of the wire , assuming the density of copper to be 8.88g per cm3

It can be observed that 1 round of wire will cover 3 mm height of cylinder.

Length of wire required in 1 round = Circumference of base of cylinder

= 2πr = 2π × 5 = 10π

Length of wire in 40 rounds = 40 × 10π

= 1257.14 cm = 12.57 m

Radius of wire= .0.3/2 = 0.15

Volume of wire = Area of cross-section of wire × Length of wire

= π(0.15)2 × 1257.14

= 88.898 cm3

Mass = Volume × Density

= 88.898 × 8.88

= 789.41 gm