Magnetic poles cannot be isolated 2 When a bar magnet of dipole moment m is placed in a uniform magnetic
field B,
Rationalised 2023-24
Physics
150
     (a)
the force on it is zero,
     (b)
the torque on it is m × B,
     (c)
its potential energy is –m B, where we choose the zero of energy at
the orientation when m is perpendicular to B