Magnetic dipole

A magnetic field source whose leading external field has the geometry of a small bar magnet or current loop. It is characterized by a magnetic dipole moment, a vector that sets the field’s strength and orientation.

Magnetic dipole moment: A vector measure of a magnetic source’s strength and orientation. It sets the strength and axis of the field attributed to a magnetic dipole.
Electric current: The rate at which electric charge flows through a surface. A circulating current creates a magnetic dipole moment.
Magnetic compass: A navigation instrument whose magnetized needle aligns approximately with Earth’s magnetic field. Its needle behaves approximately as a magnetic dipole in the geomagnetic field.
Magnetic quadrupole: A magnetic field configuration described by the quadrupole term in a multipole expansion. It has more complex angular structure and decays faster with distance than a dipole field.
Biot–Savart law: A law giving the magnetic field produced by a steady electric current. It derives the field of a current loop, a standard physical realization of a dipole.
Current loop: An electric current flowing around a closed path. A small loop produces the canonical dipole field far from its wire.
Electron magnetic moment: The intrinsic magnetic dipole moment associated with an electron’s spin and motion. It is a microscopic magnetic dipole central to atomic and materials physics.
Magnetic field of a straight wire: The circulating magnetic field produced by a long, straight electric current. Its field geometry differs from the two-lobed pattern of a localized dipole.
Magnetic vector potential: A vector field whose curl gives the magnetic field. Its dipole solution provides a compact description of the same external field.
Ampère's circuital law: A relation connecting magnetic fields around a closed path to enclosed current. It links the currents inside a source to the surrounding magnetic field.

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