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magnetic permeability ... magpie-robin

magnetic permeability: relative increase or decrease in the resultant magnetic field inside a material compared with the magnetizing field in which the given material is located; or the property of a material that is equal to the magnetic flux density B established ...
magnetic pole: region at each end of a magnet where the external magnetic field is strongest. A bar magnet suspended in the Earth's magnetic field orients itself in a north-south direction. The north-seeking pole of such a magnet, or any similar pole, ...
magnetic recording: method of preserving sounds, pictures, and data in the form of electrical signals through the selective magnetization of portions of a magnetic material. The principle of magnetic recording was first demonstrated by the Danish engineer Valdemar Poulsen in 1900, when ...
magnetic resonance: absorption or emission of electromagnetic radiation by electrons or atomic nuclei in response to the application of certain magnetic fields. The principles of magnetic resonance are applied in the laboratory to analyze the atomic and nuclear properties of matter.
magnetic Reynolds number: combination of quantities that indicates the dynamic behaviour of a plasma. This number is analogous to the Reynolds number of ordinary fluid mechanics, which is used to determine whether or not a fluid flow will smooth out or become turbulent. ...
magnetic storm: disturbance of the Earth's upper atmosphere brought on by solar flares-i.e., bright eruptions from the visible portion of the Sun's chromosphere. The material associated with these flares consists primarily of protons and electrons with an energy of a few thousand ...
magnetic survey: one of the tools used by the exploration geophysicist in his search for mineral-bearing ore bodies or even oil-bearing sedimentary structures. The essential feature is the measurement of the magnetic-field intensity and sometimes the magnetic inclination, or dip, and declination ...
magnetic susceptibility: quantitative measure of the extent to which a material may be magnetized in relation to a given applied magnetic field. The magnetic susceptibility of a material, commonly symbolized by chi_m, is equal to the ratio of the magnetization M within ...
magnetic-core storage: any of a class of computer memory devices consisting of a large array of tiny toruses of a hard magnetic material that can be magnetized in either of two directions (see computer memory).
magnetism: phenomenon associated with the motion of electric charges. This motion can take many forms. It can be an electric current in a conductor or charged particles moving through space, or it can be the motion of an electron in atomic ...
magnetite: iron oxide mineral (FeFe₂O₄, or Fe₃O₄) that is the chief member of one of the series of the spinel (q.v.) group. Minerals in this series form black to brownish, metallic, moderately hard octahedrons and masses in igneous and metamorphic rocks ...
magneto: permanent-magnet alternating generator employed when the output of energy required is very small. It is primarily designed to generate current for the ignition of compressed gases in various types of internal-combustion engines, such as those used in aircraft, marine, tractor, ...
magnetohydrodynamic power generator: any of a class of devices that generate electric current by means of the interaction of an electrically conducting fluid and a magnetic field. Various countries-including Japan, China, Poland, Russia, and the United States-have undertaken active developmental programs in magnetohydrodynamic ...
magnetohydrodynamics: the description of the behaviour of a plasma (q.v.), or, in general, any electrically conducting fluid in the presence of electric and magnetic fields.
magnetometer: instrument for measuring the strength and sometimes the direction of magnetic fields, including those on or near the Earth and in space. Magnetometers are also used to calibrate electromagnets and permanent magnets and to determine the magnetization of materials.
magneton: unit of magnetic moment (the product of a magnet's pole strength and the distance between its poles) used in the study of subatomic particles. The Bohr magneton, named for the 20th-century Danish physicist Niels Bohr, is equal to about 9.273 ...
magnetosphere: region in the atmosphere where magnetic phenomena and the high atmospheric conductivity caused by ionization are important in determining the behaviour of charged particles.
magnetostriction: change in the dimensions of a ferromagnetic material, such as iron or nickel, produced by a change in the direction and extent of its magnetization. An iron rod placed in a magnetic field directed along its length stretches slightly in ...
magnetron: diode vacuum tube consisting of a cylindrical (straight wire) cathode and a coaxial anode, between which a dc (direct current) potential creates an electric field. A magnetic field is applied longitudinally by an external magnet. Connected to a resonant line, ...
Magnificat: in Christianity, the hymn of praise by Mary, the mother of Jesus, found in Luke 1:46-55 and incorporated into the liturgical services of the Western churches (at Vespers) and of the Eastern Orthodox churches (at the morning services). Though some ...
magnification: in optics, the size of an image relative to the size of the object creating it. Linear (sometimes called lateral or transverse) magnification refers to the ratio of image length to object length measured in planes that are perpendicular to ...
Magnitogorsk: city, Chelyabinsk oblast (province), western Russia, on both banks of the Ural River. It was founded in 1929 to exploit the rich magnetite iron ore of Mt. Magnitnaya, just east of the city. The gigantic iron- and steelworks, several times ...
magnitude: in astronomy, measure of the brightness of a star or other celestial body. The brighter the object, the lower the number assigned as a magnitude. In ancient times, stars were ranked in six magnitude classes, the first magnitude class containing ...
magnolia: any member of the genus Magnolia (family Magnoliaceae; order Magnoliales), about 80 species of trees and shrubs native to North and Central America, the Himalayas, and eastern Asia. They are valued for their large and fragrant white, yellow, pink, or ...
Magnolia: city, seat (1853) of Columbia county, southwestern Arkansas, U.S. It is on the West Gulf Coastal Plain between Texarkana and El Dorado, about 80 miles (129 km) northeast of Shreveport, Louisiana. Founded in 1853, it was named for the southern ...
Magnoliaceae: magnolia family of the order Magnoliales that contains 12 genera and 210 species, including many handsome, fragrant-flowering trees and shrubs. Most have simple leaves and an elongated conelike floral axis with flowers that have six tepals (sepals and petals that ...
Magnoliales: magnolia order of dicotyledonous flowering plants, a division of the subclass Magnoliidae. The order, which is generally regarded as including the most primitive angiosperms, contains 10 families, 181 genera, and about 3,050 species. All are woody shrubs, climbers, or trees. ...
Magnoliidae: subclass of woody or herbaceous flowering plants belonging to the class Magnoliopsida.
Magnoliophyta: the division of the angiosperms, or flowering plants, which constitute the greatest number of species and occupy the widest range of habitats among all plant groups. Members range in size from the tiny duckweed (Lemna minor) to ...
Magnoliopsida: one of two classes of the division Magnoliophyta, or angiosperms, the other class being the Liliopsida (monocotyledons, or monocots). Magnoliopsida is the larger of the two classes, containing approximately 175,000 species, although this number increases as exploration of the biodiversity ...
magnon: small quantity of energy corresponding to a specific decrease in magnetic strength that travels as a unit through a magnetic substance.
Magnus effect: generation of a sidewise force on a spinning cylindrical or spherical solid immersed in a fluid (liquid or gas) when there is relative motion between the spinning body and the fluid. Named after the German physicist and chemist H.G. Magnus, ...
Magnus I: king of Sweden (1275-90) who helped introduce a feudal class society into Sweden.
Magnus I Olafsson: Norwegian ruler, king of Norway (1035-47) and Denmark (1042-47), who wrested hegemony in the two Scandinavian nations from descendants of Canute the Great (d. 1035), king of Denmark and England.
Magnus II Eriksson: king of Sweden (1319-63) and of Norway (1319-55, as Magnus VII) who devoted himself to defending his Swedish sovereignty against rebellious nobles aided by various foreign leaders, most notably Valdemar IV Atterdag, king of Denmark.
Magnus II Haraldsson: joint king of Norway with his brother Olaf III Haraldsson, from 1066 until 1069. He was a son of Harald III Haraldsson.
Magnus III: king of Norway (1093-1103), warrior who consolidated Norwegian rule in the Orkney and Hebrides islands and on the Isle of Man (all now part of the United Kingdom). He was called Barefoot (i.e., bareleg) because he often wore Scottish kilts.
Magnus IV: joint ruler of Norway (1130-35), with Harald IV, whose abortive attempt (1137-39) to wrest sovereignty from Inge I Haroldsson and Sigurd II, sons of Harald IV, ended the first epoch in the period of Norwegian civil wars (1130-1240).
Magnus V Erlingsson: king of Norway (1162-84) who used church support to gain the throne (1162) and become the nation's first crowned monarch (1163). After 1177 his rule was challenged by his rival Sverrir, whose forces killed Magnus in battle.
Magnus VI: king of Norway (1263-80) who transformed the nation's legal system by introducing new national, municipal, and ecclesiastical codes, which also served as a model for many of the Norwegian colonies. His national code was used for more than 400 years.
Magnus, Johannes: Roman Catholic archbishop and historian, one of the most distinguished scholars of his time, who was exiled as a consequence of the Reformation.
Magnus, Olaus: Swedish ecclesiastic and author of an influential history of Scandinavia.
Magnusson, Arni: Scandinavian antiquarian and philologist who built up the most important collection of early Icelandic literary manuscripts.
Magnusson, Jon: Icelandic parson and author of the Pislarsaga ("Passion Story"), one of the strangest documents of cultural and psychic delusion in all literature.
Mago: a leading Carthaginian general during the Second Punic War (218-201 BC) against Rome. He was the youngest of the three sons of the Carthaginian statesman and general Hamilcar Barca.
Magog: city, Estrie region, southern Quebec province, Canada, lying along the Magog River, near the foot of Lake Memphremagog, 20 miles (32 km) north of the border with Vermont, U.S. The townsite, originally an Indian camp, was a stopping place on ...
Magog: in biblical and apocalyptic literature, a hostile power associated with Gog (q.v.).
Magosian industry: stone-tool technology in which an advanced Levallois technique was employed for the production of flakes for the manufacture of other tools, together with a punch technique for the production of microlithic artifacts. Projectile points were produced by pressure flaking.
magpie: any of several long-tailed birds belonging to the family Corvidae (order Passeriformes). The best-known species, often called the black-billed magpie (Pica pica), is a 45-centimetre (18-inch) black-and-white (i.e., pied) bird, with an iridescent blue-green tail. It occurs in northwestern Africa, ...
magpie goose: (Anseranas semipalmata), large aberrant waterfowl of Australia and Papua New Guinea, the sole member of the subfamily Anseranatinae, family Anatidae (order Anseriformes). The sexes are alike in having a black-and-white body (hence "magpie"), long neck, long legs, and virtually unwebbed ...
magpie-robin: any of eight species of chat-thrushes, belonging to the family Turdidae (order Passeriformes), found in southern Asia. They are 18 to 28 cm (7 to 11 inches) long, with pied plumage and attenuated tails-small replicas of magpies. The uptilted tail ...