This page lists examples of magnetic moments produced by various sources, grouped by orders of magnitude. 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 a large magnetic moment, but due to the radial distance, we experience only a tiny magnetic flux density on its surface.
Knowing the magnetic moment of an object () and the distance from its centre () it is possible to calculate the magnetic flux density experienced () using the following approximation:
where is the vacuum permeability constant.
Examples +Magnetic dipole moments Factor (m2⋅A) Value Item 10−47 That is, Unit of magnetic moment in Stoney units 10−45 That is, Unit of magnetic moment in Planck units 10−43 ~ See in particular equation (5): , where is one of the possible neutrino masses, is Fermi's constant and is Bohr magneton. Expected magnetic moment of a neutrino 10−27 Magnetic moment of a deuterium nucleus 10−26 Magnetic moment of a proton 10−24 Magnetic moment of a positron Bohr magneton 10−18 0.65–2.65 nm2⋅A (1 nm2⋅A = 10−18 m2⋅A) Magnetic moment of individual magnetite nanoparticles (20 nm diameter) 10−14 Magnetic moment of magnetotactic bacteria 10−13 10−11 Magnetic moment of the human brain 10−5 NIST YIG (yttrium iron garnet) standard 1 mm sphere for calibrating magnetometers (SRM #2852) 10−4 Needle in a thumbnail-sized compass 10−3 Neodymium–iron–boron disc in a typical mobile phone 10−1 A typical refrigerator magnet Neodymium–iron–boron (strongest grade) disc the same size as a US penny 100 Neodymium–iron–boron N35 magnet with a volume of 1 cm3 Neodymium–iron–boron N52 magnet with a volume of 1 cm3 103 A bowling ball made of neodymium–iron–boron (strongest grade) 106 This is a consequence of the definition of the magnetic constant. A magnet that produces one tesla one metre away from its centre 1012 A magnet that produces one tesla 100 m away from its centre 1015 Magnetic moment of the Moon 1016 1019 Magnetic moment of Mercury 1020 Magnetic moment of Ganymede 1022 Magnetic moment of Earth 1024 Magnetic moment of Neptune Magnetic moment of Uranus 1025 Magnetic moment of Saturn 1027 Magnetic moment of Jupiter 1028 Magnetic moment of a star, a white dwarf or a magnetarMagnetars have enormous magnetic flux densities on their surfaces due to the small radius, however the total magnetic field of the original star does not increase during the collapse, but actually decreases with time. Cf. 1029 1030
References
See also Orders of magnitude (magnetic flux density)