Given
Radius of copper rod (r) = 1 cm
Length of the copper rod (l) = 2 cm
∴ Volume of copper rod = πr2h = π × (1)2 × 2
= 2 π cm3
the Length of the wire (l1) = 18 meter
= 1800 cm
If the radius of transverse section of wire be R
The volume of wire = πR2h = πR2 × 1800
R = \(\frac { 1 }{ 30 }\) cm
Diameter of wire = 2R = 2 × \(\frac { 1 }{ 30 }\) = \(\frac { 1 }{ 15 }\) cm
Hence, the thickness of the wire
= diameter = \(\frac { 1 }{ 15 }\) cm
= 0.67 cm(approx)
