A bar magnet placed in a uniform magnetic field experience no force but experience torque

In a non-uniform magnetic field a bar magnet experiences a force as well as a torque

The potential energy is maximum when magnetic dipole moment $\vec{M}$ is parallel to magnetic field $\vec{B}$

The work done in rotating a magnet in a uniform magnetic field from $Q_1$ to $Q_2$ is W = MB $(cos \theta_1 =cos \theta_2)$