External Magnetic Field Produced By A Magnetic Dipole Moment
In classical physics, the magnetic field of a dipole is calculated as the limit of either a current loop or a pair of charges as the source shrinks to a point while keeping the magnetic moment m constant. For the current loop, this limit is most easily derived for the vector potential. Outside of the source region, this potential is (in SI units)
and the magnetic flux density (strength of the B-field) in teslas is
Alternatively one can obtain the scalar potential first from the magnetic pole limit,
and hence the magnetic field strength (or strength of the H-field) in ampere-turns per meter is
The magnetic field is symmetric under rotations about the axis of the magnetic moment.
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