A circular coil of 100 turns has an effective radius of 0.05 m and carries a current of 0.1 A. How much work is required to turn it in an external magnetic field of `1.5 Wb m^-2` through `180^@` about an axis perpendicular to the magnetic field. The plane of the coil is initially perpendicular to the magnetic field.

Answer

A, C

Explanation

`U_(i)=-MB`
`U_(f)=+MB`
`U_(i)=+MB`
`U_(f)=-MB`
`W=DeltaU=2MB`
`=2xxNi pi r^(2)B`
`W=+-75pixx10^(-3)J`