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In electromagnetism, the magnetic moment or magnetic dipole moment is the combination of strength and orientation of a magnet or other object or system that exerts a magnetic field. The magnetic dipole moment of an object determines the magnitude of torque the object experiences in a given magnetic field. When the same magnetic field is applied ...
The total magnetic dipole moment resulting from both spin and orbital angular momenta of an electron is related to the total angular momentum J by a similar equation: = . The g -factor g J is known as the Landé g -factor , which can be related to g L and g S by quantum mechanics.
Objects with a magnetic moment also have angular momentum and effective internal electric current proportional to their angular momentum; these include electrons, protons, other fermions, many atomic and nuclear systems, as well as classical macroscopic systems. The external magnetic field exerts a torque on the magnetic moment,
While the transfer of angular momentum on a magnetic moment from an applied magnetic field is shown to cause precession of the moment about the field axis, the rotation of the moment into alignment with the field occurs through damping processes. Atomic-level dynamics involves interactions between magnetization, electrons, and phonons. [3]
The magnetic moment of an object is an intrinsic property and does not change with distance, and thus can be used to measure "how strong" a magnet is. For example, Earth possesses an enormous magnetic moment, however we are very distant from its center and experience only a tiny magnetic flux density (measured in tesla ) on its surface.
Angular momentum (sometimes called moment of momentum or rotational momentum) is the rotational analog of linear momentum.It is an important physical quantity because it is a conserved quantity – the total angular momentum of a closed system remains constant.
The interaction of the neutron's magnetic moment with an external magnetic field was exploited to determine the spin of the neutron. [47] In 1949, D. Hughes and M. Burgy measured neutrons reflected from a ferromagnetic mirror and found that the angular distribution of the reflections was consistent with spin 1 / 2 . [48]
Nuclear magnetic resonance (NMR) spectroscopy uses the intrinsic magnetic moment that arises from the spin angular momentum of a spin-active nucleus. [1] If the element of interest has a nuclear spin that is not zero, [1] the nucleus may exist in different spin angular momentum states, where the energy of these states can be affected by an external magnetic field.