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Curie temperature: The characteristic temperature T c above which the remanence of polarization in a ferro-magnetic material becomes Jr = 0. o gastroenterologista cuida do que At temperatures above the Curie temperature all ferromagnetic materials are paramagnetic. However, the maximum temperature for the use of magnetic materials is usually much lower than the Curie temperature and is determined by changes in composition, self-demagnetization, the decay of bonding materials and other physical effects (see also Temperature, operating).

Losses, reversible, irreversible: The changes in the magnetic values which occur in magnets, for example due to the influence of external temperatures, may be reversible or irreversible. In the case of reversible changes, unlike irreversible changes, the magnetic properties revert to their original values when the initial temperature is restored.

Magnetism: Sum of magnetic phenomena arising from the electromagnetic interactions (force) and one of the fundamental physical forces. gas utility boston It is described in terms of the magnetic field H and the magnetic flux density B. All magnetic phenomena are associated with moving electrical charges (i.e. with electrical currents) while the term electrostatics describes the forces which occur between non-moving electrical charges. Finally, the term electrodynamics relates to the association between varying electrical and magnetic fields.

When a material is magnetized, the polarization J defines an alignment of magnetic moments. These moments consist of the moments of trajectory of the electrons circling the atomic nucleus and the so-called electron spin which is caused by the rotation of the electron around its own axis. If these moments are self-compensating for all the atoms then the material is termed diamagnetic. gas prices going up to 5 dollars In the case of para-, ferro-, antiferro- and ferrimagnetic materials, the sum of these moments is different from zero. They differ from one another in the way the moments of neighboring atoms are coupled: in the case of paramagnetism there is no coupling; in ferromagetism, the neighbouring atomic moments are parallel, in antiferromagnetism they have an antiparallel alignment. gas tax in washington state The term ferrimagnetism is used when the atomic moments in antiparallel alignment do not fully compensate for one another and the resulting magnetism persists.

Moment, magnetic: (also dipole moment) Product of polarization J and volume V of a homogeneously magnetized magnet. The moment, expressed in terms of Vsm, corresponds to the mechanical torque in Nm experienced by the magnet in a magnetic field H of 1 A/m perpendicular to the magnetization (Coulomb’s magnetic moment m Coul). The magnetic moment is measured directly in a Helmholtz coil in combination with a fluxmeter. (see also SI units) Formerly the Ampere magnetic moment m Amp was commonly used as the product of the magnetization M and volume V of a solid, where m Coul=μ 0 m Amp.

Permeability: μ = B/H; ratio of the flux density B to the magnetic field H. electricity drinking game In permanent magnet technology, permanent permeability is important as this gives the change in B when small changes in H occur ( u p = dB/dH), in particular close to the optimum working point. Unit: 1 T m/A. The permeability of a vacuum is μ 0 = 1.256-10 -6 T/m = 1.256 * 10 -6 Vs/Am.

Polymer bonded magnet material: If a magnet powder is blended with plastic material it is possible to apply methods used in the plastic industry (injection molding, rolling, extrusion) to produce magnets of very complex shapes. The advantages: cheap manufacturing processes, small tolerances and many kinds of shapes must be compared with the disadvantages: expensive tools and lower magnetic properties.

Preferred orientation: Orientation, resulting from the production process, in a magnet in which the magnetic properties are at their highest level. gas in dogs causes Magnets with a preferred orientation ( anisotropic materials) can only be magnetized in this orientation, whereas isotropic materials can be magnetized in any direction using appropriate equipment/coils.

SI units: Physical units according to the System International (SI) which is based on the units kilogram, meter second and ampere. All other units are expressed as a product, a quotient or a power of these four basic units. The older cgs units (cm, gram, second) and the Gauß units in the field of magnetism are still in use but their adaptation is now a legal requirement. electricity in the 1920s The following table indicates some magnetic units and their conversion.

Tolerances, magnetic: According to DIN 17410, magnetic materials are characterized by minimum values. Although no upper limits are defined, most materials typically lie in the range up to 114% of minimum remanence and up to 125% of minimum energy product. If the magnetic values are subject to more precisely defined requirements, then it is advisable to perform (very time-consuming) comparisons during the magnetization process.

XMR effect: Sum total of the AMR, GMR and CMR effects. These are huge changes of electric resistance within thin layers of different materials exposed to a magnetic field and are utilized in sensors which are used to capture/measure the strength and orientation of magnetic fields. gas efficient suv 2013 As they were discovered, the increasingly strong effects were named, in succession, magneto resistive effect, AMR effect, GMR effect, CMR effect.