Multiple choice

A copper wire $3:mm$ in diameter is rounded about a cylinder whose length is $1.2:m$ and diameter is $10:cm$., so as to cover the curved surface of the cylinder. The length of the wire is

  1. $125.6\:m$
  2. $1256\:m$
  3. $12.56\:m$
  4. $1.256\:m$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Length of cylinder = 1.2m = 120cm. Diameter = 10cm. Circumference = pi * 10 = 31.4cm. Number of turns = 120cm / 0.3cm = 400 turns. Total length = 400 * 31.4cm = 12560cm = 125.6m.

AI explanation

To find the length of the wire, we divide the curved surface area of the cylinder by the thickness, or diameter, of the wire. The curved surface area of the cylinder is pi * diameter * length, which is (22 / 7) * 10 * 120, equalling 3771.43 sq cm. Since the wire is 3 mm or 0.3 cm thick, the number of turns is 120 / 0.3 = 400, and the circumference of one turn around the cylinder is pi * 10 cm, making the total length 400 * (22 / 7) * 10 cm, which equals 12571.4 cm or 125.6 m.

Keep practicing — related questions