Question
A bar magnet having a magnetic moment of 2 x 104 JT-1 is free to rotate in a horizontal plane. A horizontal magnetic field B = 6 x 10-4 T exists in the space. The work is done in taking the magnet slowly from a direction parallel to the field to a direction 60o from the field is
-
0.6 J
-
12 J
-
6 J
-
2 J
Solution
C.
6 J
The work done in rotating a magnetic dipole against the torque acting on it, when placed in a magnetic field is stored inside it in the form of potential energy.
When magnetic dipole is rotated from initial position θ = θ1 to final position θ = θ2, then work done = MB (cos θ1 = cos θ2)
