Question

A copper wire of diameter 5 mm is evenly wrapped on a cylinder of length 15 cm to cover its whole surface. The number of wrap will be :

(A) 75

(B) 50

(C) 45

(D) 30

Answer 1

Answer is (D) 30

Given,

Diameter of wire = 5 mm = \(\frac { 5 }{ 10 }\) cm

length of the cylinder = 15 cm

∴ Number of wrap

∴ Number of wrap = 30.