Write the equation of potential energy of a bar magnet placed in a uniform magnetic field.

(N/A) The potential energy $U$ of a bar magnet with magnetic moment $\vec{m}$ placed in a uniform magnetic field $\vec{B}$ is given by the dot product of the magnetic moment and the magnetic field:
$U = -\vec{m} \cdot \vec{B}$
Alternatively,it can be expressed as:
$U = -mB \cos \theta$
where $\theta$ is the angle between the magnetic moment vector $\vec{m}$ and the magnetic field vector $\vec{B}$.