A bar magnet of magnetic moment 1 . 5   J   T - 1 is aligned with the direction of a uniform magnetic field of 0 . 22   T . The work done in turning the magnet so as to align its magnetic moment opposite to the field and the torque acting on it in this position are respectively.

Step-by-step solution

Potential energy of a magnetic dipole is given as U   =   - M B   cos θ where, M =   M a g n e t i c   d i p o l e ,   B =   M a g n e t i c   f i e l d ,   θ   =   A n g l e   b e t w e e n   M →   a n d   B → W =   U f - U i   ⇒ W   =   - M B   cos θ f   -   - M B   cos θ i ⇒ W   =   M B   cos θ i -   cos θ f ⇒ W   =