One tool for determining the direction of the velocity vector of a moving charge, the magnetic field, and the force exerted is labeling the index finger "V" [ dubious – discuss], the middle finger "B", and the thumb "F" with your right hand. When making a gun-like configuration, with the middle finger crossing under the index finger, the fingers represent the velocity vector, magnetic field vector, and force vector, respectively. See also right-hand rule. Coey, J. M. D. (2019). Magnetism and Magnetic Materials. Cambridge University Press. ISBN 978-1108717519. You may have noticed that the materials that make good magnets are the same as the materials magnets attract. This is because magnets attract materials that have unpaired electrons that spin in the same direction. In other words, the quality that turns a metal into a magnet also attracts the metal to magnets. Many other elements are diamagnetic — their unpaired atoms create a field that weakly repels a magnet. A few materials don't react with magnets at all. The stronger magnetic fields can be hazardous to mechanical and electronic devices, as they can erase magnetic media such as floppy disks and credit cards, and magnetize watches and the shadow masks of CRT type monitors at a greater distance than other types of magnet. In some cases, chipped magnets can act as a fire hazard as they come together, sending sparks flying as if they were a lighter flint, because some neodymium magnets contain ferrocerium.

In process industries, powerful neodymium magnets are used to catch foreign bodies and protect product and processes [32] Huang, S. "Why Don't Magnets Work on Some Stainless Steels?" Scientific American. Oct. 2, 2006. (Sept. 5, 2022). https://www.scientificamerican.com/article/why-dont-magnets-work-on/According to the Heitler–London theory, so-called two-body molecular σ {\displaystyle \sigma } -orbitals are formed, namely the resulting orbital is: I.e., not only u A {\displaystyle u_{A}} and u B {\displaystyle u_{B}} must be substituted by α and β, respectively (the first entity means "spin up", the second one "spin down"), but also the sign + by the − sign, and finally r i by the discrete values s i (=± 1⁄ 2); thereby we have α ( + 1 / 2 ) = β ( − 1 / 2 ) = 1 {\displaystyle \alpha (+1/2)=\beta (-1/2)=1} and α ( − 1 / 2 ) = β ( + 1 / 2 ) = 0 {\displaystyle \alpha (-1/2)=\beta (+1/2)=0} . The " singlet state", i.e. the − sign, means: the spins are antiparallel, i.e. for the solid we have antiferromagnetism, and for two-atomic molecules one has diamagnetism. The tendency to form a (homoeopolar) chemical bond (this means: the formation of a symmetric molecular orbital, i.e. with the + sign) results through the Pauli principle automatically in an antisymmetric spin state (i.e. with the − sign). In contrast, the Coulomb repulsion of the electrons, i.e. the tendency that they try to avoid each other by this repulsion, would lead to an antisymmetric orbital function (i.e. with the − sign) of these two particles, and complementary to a symmetric spin function (i.e. with the + sign, one of the so-called " triplet functions"). Thus, now the spins would be parallel ( ferromagnetism in a solid, paramagnetism in two-atomic gases). Here the last product means that a first electron, r 1, is in an atomic hydrogen-orbital centered at the second nucleus, whereas the second electron runs around the first nucleus. This "exchange" phenomenon is an expression for the quantum-mechanical property that particles with identical properties cannot be distinguished. It is specific not only for the formation of chemical bonds, but also for magnetism. That is, in this connection the term exchange interaction arises, a term which is essential for the origin of magnetism, and which is stronger, roughly by factors 100 and even by 1000, than the energies arising from the electrodynamic dipole-dipole interaction. The Nd 2Fe 14B crystal structure can be described as alternating layers of iron atoms and a neodymium-boron compound. [2] The diamagnetic boron atoms do not contribute directly to the magnetism but improve cohesion by strong covalent bonding. [2] The relatively low rare earth content (12% by volume, 26.7% by mass) and the relative abundance of neodymium and iron compared with samarium and cobalt makes neodymium magnets lower in price than samarium–cobalt magnets. [2]

The Dependence of Magnetic Properties and Hot Workability of Rare Earth-Iron-Boride Magnets Upon Composition. Cunningham, Aimee. "Magnet Makeover." Science News. Jan. 30, 2007. (Sept. 5, 2022) https://www.sciencenews.org/article/magnet-makeover M. Sagawa; S. Fujimura; N. Togawa; H. Yamamoto; Y. Matsuura (1984). "New material for permanent magnets on a base of Nd and Fe (invited)". Journal of Applied Physics. 55 (6): 2083. Bibcode: 1984JAP....55.2083S. doi: 10.1063/1.333572. Neodymium Magnets (NdFeb, NIB, Neo), also known as “rare earth magnets,” are composed of neodymium, iron, boron, and transition metals. Despite their small size, these magnets are incredibly powerful and are the strongest magnetic material available. Neodymium magnets should be handled with care to avoid injury and can be used in a variety of environments and magnetic assemblies. In ancient China, the earliest literary reference to magnetism lies in a 4th-century BC book named after its author, Guiguzi. [8]

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The location of Magnesia is debated; it could be the region in mainland Greece or Magnesia ad Sipylum. See, for example, "Magnet". Language Hat blog. 28 May 2005 . Retrieved 22 March 2013. The two sources of magnetism are electric current and spin magnetic moments of elementary particles (primarily electrons).

In 1600, William Gilbert published his De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure ( On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth). In this work he describes many of his experiments with his model earth called the terrella. From his experiments, he concluded that the Earth was itself magnetic and that this was the reason compasses pointed north whereas, previously, some believed that it was the pole star Polaris or a large magnetic island on the north pole that attracted the compass.Electromagnetism has continued to develop into the 21st century, being incorporated into the more fundamental theories of gauge theory, quantum electrodynamics, electroweak theory, and finally the standard model. The quantities now used in characterizing magnetization were defined and named by William Thomson ( Lord Kelvin) in 1850. The symbol B denotes the magnitude of magnetic flux density inside a magnetized body, and the symbol H denotes the magnitude of magnetizing force, or magnetic field, producing it. The two are represented by the equation B = μ H, in which the Greek letter mu, μ, symbolizes the permeability of the material and is a measure of the intensity of magnetization that can be produced in it by a given magnetic field. The modern units of the International Standard (SI) system for B are teslas (T) or webers per square metre (Wb/m 2) and for H are amperes per metre (A/m). The units were formerly called, respectively, gauss and oersted. The units of μ are henrys per metre. The strength and magnetic field homogeneity on neodymium magnets has also opened new applications in the medical field with the introduction of open magnetic resonance imaging (MRI) scanners used to image the body in radiology departments as an alternative to superconducting magnets that use a coil of superconducting wire to produce the magnetic field. [36]