Magnetic moment, also known as magnetic dipole moment, is a measure of the strength of a permanent magnet or a current-carrying coil expressed as the torque product when the magnet or coil is set with its axis perpendicular to a unit magnetic field; in other words, it is the maximum turning force exerted on a magnet or coil (or moving electric charge) in a magnetic field divided by the strength of the field. Charged particles and atomic nuclei also have magnetic moments.