Question

A copper wire 3mm in diameter is wound about a cylinder whose length is 1.2m and diameter 10cm so as to cover the curved surface of the cylinder. Find the length of the wire used.

Answer 1

curved surface area of the cyclinder=2πrh=2×3.14×5×12 cm^2 =120×3.14 cm^2
width of wire=3mm=3/10 cm
area of wire =l×3/10cm ^2
l×3/10=120×3.14
l=1203.14×10/3 cm =12560 cm

Answer 2

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