Magnetics 2 Question 10
10. A long insulated copper wire is closely wound as a spiral of turns. The spiral has inner radius and outer radius . The spiral lies in the plane and a steady current flows through the wire. The -component of the magnetic field at the centre of the spiral is
(2011)
(a)
(b)
(c)
(d)
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Answer:
Correct Answer: 10. (a)
Solution:
- If we take a small strip of
at distance from centre, then number of turns in this strip would be,
Magnetic field due to this element at the centre of the coil will be