| 单词 | magnetic permeability |
| 释义 | > as lemmasmagnetic permeability magnetic permeability n. see permeability n. 1b. magnetic permeability 2. Physics. (More fully magnetic permeability) one of the physical parameters of a medium, equal to the ratio of the magnetic induction B to the magnetic field strength H at any point in it (symbol μ; SI unit, henry metre−1); (also, more fully relative permeability) the ratio of the magnetic permeability of a medium to that of free space; permeability of free space n. a constant μ0 which in the cgs electromagnetic system of units is one and in the SI System is defined as a base quantity with the value 4π (= 12.57) × 10−7 henry metre−1.Of the different permeabilities mentioned in quot. 1872, the magnetic kind is the only one that gained currency. ΘΚΠ the world > matter > physics > electromagnetic radiation > electricity > electrically induced magnetism > electromagnetic induction > [noun] > conducting power permeability1872 permeance1885 perviability1895 the world > matter > physics > electromagnetic radiation > magnetism > [noun] > magnetic field > lines of magnetic force > conducting power of magnetic permeability1872 perviability1895 the world > matter > physics > electromagnetic radiation > electricity > electrically induced magnetism > electromagnetic induction > [noun] > conducting power > constant permeability of free space1988 1872 W. Thomson in Papers Electrostatics & Magn. 484 We have thermal permeability, a synonym for thermal conductivity; permeability for lines of electric force, a synonym for the electro-static inductive capacity of an insulator; magnetic permeability, a synonym for conducting power for lines of magnetic force. 1896 F. Bedell Princ. Transformer 40 The reluctance, R, or magnetic resistance..varies..inversely as the cross-section and permeability. 1939 L. F. Bates Mod. Magn. ii. 67 Pure iron has an initial permeability of about 250. 1942 London, Edinb. & Dublin Philos. Mag. 7th Ser. 33 488 The universal constant 1/ac2 occurring in (12.2) has the value..1/107 ohm sec./m...and is called the permeability of empty space. Consistency practically compels us to call the constant μ/ac2 in (12.3) the permeability of the medium. 1944 London, Edinb., & Dublin Philos. Mag. 7th Ser. 35 83 Guggenheim has suggested the term permittivity for the fundamental quantity and specific inductive capacity or dielectric constant for the derived quantity. In conformity with the other suggestions in this paper it would be more uniform to adopt permittivity and relative permittivity... Similarly in the magnetic case we have permeability and relative permeability. 1962 D. R. Corson & P. Lorrain Introd. Electromagn. Fields vii. 284 The detailed shape of the magnetization curve and the maximum permeability achieved with a given sample of iron depend on the purity, the method of annealing, and on the thickness of the sheets. 1988 J. D. Barrow & F. J. Tipler Anthropic Cosmol. Princ. (rev. ed.) iv. 282 Maxwell's equations imply charge conservation, so a change in α is most conveniently interpreted as being due to a change in the permittivity or permeability of free space. 2003 Sci. Amer. Jan. 15/1 The refractive index of a substance is determined by two properties known as the electrical permittivity and the magnetic permeability. < as lemmas |
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