A circular coil of radius 4 cm has 50 turns. In this coil a current of 2 A is flowing. It is placed in a magnetic field of 0.1 \[weber/{{m}^{2}}\]. The amount of work done in rotating it through \[180{}^\circ \] from its equilibrium position will be [CPMT 1977]

• A.            0.1 J                                         
• B.            0.2 J
• C.            0.4 J                                         
• D.            0.8 J