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Matteucci Effect
Matteucci effect is one of the magnetomechanical effects, which is thermodynamically inverse to Wiedemann effect. This effect was described by Carlo Matteucci in 1858. It is observable in amorphous wires with helical domain structure, which can be obtained by twisting the wire, or annealing under twist. The effect is most distinct in the so-called 'dwarven alloys' (called so because of the historical cobalt element etymology), with cobalt as main substituent. See also * Magnetostriction * Magnetocrystalline anisotropy In physics, a ferromagnetic material is said to have magnetocrystalline anisotropy if it takes more energy to magnetize it in certain directions than in others. These directions are usually related to the principal axes of its crystal lattice. I ... References {{reflist Magnetism Magnetic ordering ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetomechanical Effects
{{Unreferenced, date=May 2019, bot=noref (GreenC bot) Magnetomechanical effects connect magnetic, mechanical and electric phenomena in solid materials. * Magnetostriction * Inverse magnetostrictive effect * Wiedemann effect * Matteucci effect * Guillemin effect Magnetostriction is thermodynamically opposite to inverse magnetostriction effect. The same situation occurs for Wiedemann and Matteuci effects. For magnetic, mechanical and electric phenomena in fluids see Magnetohydrodynamics and Electrohydrodynamics. See also * Magnetocrystalline anisotropy In physics, a ferromagnetic material is said to have magnetocrystalline anisotropy if it takes more energy to magnetize it in certain directions than in others. These directions are usually related to the principal axes of its crystal lattice. I ... Magnetism Magnetic ordering ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wiedemann Effect
The twisting of a ferromagnetic rod through which an electric current is flowing when the rod is placed in a longitudinal magnetic field. It was discovered by the German physicist Gustav Wiedemann in 1858 . The Wiedemann effect is one of the manifestations of magnetostriction in a field formed by the combination of a longitudinal magnetic field and a circular magnetic field that is created by an electric current. If the electric current (or the magnetic field) is alternating, the rod will begin torsional oscillation. In linear approach angle of rod torsion ''α'' does not depend on its cross-section form and is defined only by current density and magnetoelastic properties of the rod: :\alpha = j \frac, where * j is current density; * h_ is magnetoelastic parameter, proportional to longitudinal magnetic field value; * G is the shear modulus. Applications Magnetostrictive position sensors use the Wiedemann effect to excite an ultrasonic pulse. Typically a small magnet is used t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carlo Matteucci
Carlo Matteucci (20 or 21 June 1811 – 25 June 1868) was an Italian physicist and neurophysiologist who was a pioneer in the study of bioelectricity. Biography Carlo Matteucci was born at Forlì, in the province of Romagna, to Vincenzo Matteucci, a physician, and Chiara Folfi. He studied mathematics at the University of Bologna from 1825 to 1828, receiving his doctorate in 1829. From 1829 to 1831, he studied at the École Polytechnique in Paris, France. Upon returning to Italy, Matteucci studied at Bologna (1832), Florence, Ravenna (1837) and Pisa. He established himself as the head of the laboratory of the Hospital of Ravenna and became a professor of physics at the local college. In 1840, by recommendation of François Arago (1786–1853), his teacher at the École Polytechnique, to the Grand-Duke of Tuscany, Matteucci accepted a post of professor of physics at the University of Pisa. Instigated by the work of Luigi Galvani (1737–1798) on bioelectricity, Matteucci bega ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. Cobalt-based blue pigments ( cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was for a long time thought to be due to the known metal bismuth. Miners had long used the name ''kobold ore'' (German for ''goblin ore'') for some of the blue-pigment-producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the ''kobold''. Today, some cobalt is produced specifically from one of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetostriction
Magnetostriction (cf. electrostriction) is a property of magnetic materials that causes them to change their shape or dimensions during the process of magnetization. The variation of materials' magnetization due to the applied magnetic field changes the magnetostrictive strain until reaching its saturation value, λ. The effect was first identified in 1842 by James Joule when observing a sample of iron. This effect causes energy loss due to frictional heating in susceptible ferromagnetic cores. The effect is also responsible for the low-pitched humming sound that can be heard coming from transformers, where oscillating AC currents produce a changing magnetic field. Explanation Internally, ferromagnetic materials have a structure that is divided into '' domains'', each of which is a region of uniform magnetization. When a magnetic field is applied, the boundaries between the domains shift and the domains rotate; both of these effects cause a change in the material's dimensions. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetocrystalline Anisotropy
In physics, a ferromagnetic material is said to have magnetocrystalline anisotropy if it takes more energy to magnetize it in certain directions than in others. These directions are usually related to the principal axes of its crystal lattice. It is a special case of magnetic anisotropy. In other words, the excess energy required to magnetize a specimen in a particular direction over that required to magnetize it along the easy direction is called crystalline anisotropy energy. Causes The spin-orbit interaction is the primary source of magnetocrystalline anisotropy. It is basically the orbital motion of the electrons which couples with crystal electric field giving rise to the first order contribution to magnetocrystalline anisotropy. The second order arises due to the mutual interaction of the magnetic dipoles. This effect is weak compared to the exchange interaction and is difficult to compute from first principles, although some successful computations have been made. Pra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetism
Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. Magnetism is one aspect of the combined phenomena of electromagnetism. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Demagnetizing a magnet is also possible. Only a few substances are ferromagnetic; the most common ones are iron, cobalt, and nickel and their alloys. The rare-earth metals neodymium and samarium are less common examples. The prefix ' refers to iron because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, Fe3O4. All substances exhibit some type of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
