A circular coil of radius (10 ~cm ) with 100 turns carrying a current of (0.5 ~A ) lies in a magnetic field of (2 ~T ) such that the normal drawn to the plane of the coil makes an angles ( ) with the direction of the field. Work done in rotating the coil to change the angle ( ) from (0^ ) to (180^ ) is

Step-by-step solution

Given, radius of coil, (R=10 10⁻² ~m ), number of turns in coil, (N=100 ) turns, current through coil, (I=0.5 ~A ), magnetic field, (B=2 ~T ) and change in angle of rotating coil, ( =0^ ) to (180^ ). Work done in turning a loop from angle ( ₁ ) to ( ₂ ). ( aligned & W=M B ( ₁- ₂ ) & W=N I A B [ 0^ - 180^ ] & W=100 0.5 100 10⁻⁴ 2[1-(-1)] aligned ) Hence, (W=2 J ) ( ) The correct option is (b).