Question

A circular coil of 100 turns and effective diameter 20cm carries a current of 0.5 A. It is to be turned in a magnetic field of B = 2.0 T from a position in which the normal to the plane of the coil makes an angle $\theta$ equals to zero to one in which $\theta$ equals to 180$^\circ$. The work required in this process is

• A. $\pi\,J$
• B. $2\,\pi\,J$
• C. $4\,\pi\,J$
• D. $8\,\pi\,J$

Answer 1

Answer: (B)

$2\,\pi\,J$

Answer 2

$w=MB (1 - \cos\,\theta)$