A copper rod of diameter 1 cm and length 8 cm is drawn into a wire of length 18 m of uniform thickness. Find the thickness of the wire.
Diameter of copper wire =1 cm
Radius 
cm
Height of copper rod =Length of copper rod =8 cm
Volume of rod 
Let the radius of wire be ‘r’ cm
Height of the wire =18 m =0.18 cm
Volume of cylinder wire = Volume of cylindrical rod
⇒ r2
⇒ r 
cm
⇒ r = 1/3 mm
∴ Diameter of cross section = (1/3) × 2 mm
= 0.67 mm
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