Electromagnetic momentum of an electric dipole in a uniform magnetic field

The electromagnetic momentum of an electric dipole in a uniform magnetic field of strength B0 is equal to B0×p/2, where p is the electric moment of the dipole, provided the charge and current distributions generating the electric and magnetic fields are spatially separated. In the degenerate case where these distributions fully overlap, or else are concentrated in a single point, the electromagnetic momentum is equal to B0 × p/4. In all cases it does not matter whether the magnetic field is of finite or infinite extent. These results are obtained using three different methods which provide a test of the internal consistency of electrodynamics with regard to the handling of complicated singularities in the potentials, fields, and sources.