单词 | dipole moment) |
释义 | > as lemmas(magnetic, electric) dipole moment) c. Physics. The distance between the two poles of a simple bar magnet, or the two charges of an electric dipole, multiplied by the strength of either pole, as a measure of the turning effect produced by an applied magnetic or electric field, respectively (cf. magnetic moment n. at magnetic adj. and n. Compounds); the maximum torque that a given system of poles or charges can experience in a uniform magnetic or electric field (respectively) of unit strength (more fully (magnetic, electric) dipole moment). In extended use: (in the polynomial in 1/ R expressing the potential V at a point, where R is the distance from the point to the origin) a quantity expressed by terms in the coefficient of 1/ Rn+1 (where n=1 represents a dipole, n=2 a quadrupole, etc.; cf. multipole n.). ΘΚΠ the world > matter > physics > quantum theory > quantum mechanics > quantum electrodynamics > [noun] > multipole moment (magnetic, electric) dipole moment)1865 the world > matter > physics > electromagnetic radiation > magnetism > magnetic devices or materials > [noun] > pole of magnet > distance between poles magnetic moment1865 moment1865 the world > matter > physics > electromagnetic radiation > electricity > electrically induced magnetism > [noun] > field > dipole moment magnetic moment1865 (magnetic, electric) dipole moment)1962 1865 London, Edinb., & Dublin Philos. Mag. 4th Ser. 29 441 The product of the strength of the poles into the length between them is called the magnetic moment of the magnet. 1884 J. T. Sprague Electr. (ed. 2) iii. 110 The magnetic moment of any uniformly magnetized substance is proportional to its volume. 1903 S. J. Barnett Elem. Electromagn. Theory xi. 282 The quantity M = mL = T/H sin θ is called the magnetic moment of the magnet (analogous to the electric moment of an electret). 1916 Jrnl. Amer. Chem. Soc. 38 764 One or more electrons are held by sufficiently weak constraints so that they may..in the extreme case pass altogether to another atom, thus producing in the molecule a bipole or multipole of high electrical moment. 1932 J. H. Van Vleck Theory Electr. & Magn. Susceptibilities i. 12 The omitted terms are sometimes characterized as representing ‘multipoles’. The omitted term in ϕ of lowest order, for instance, is..Nq/R3, where q is the ‘quadrupole moment’. 1953 Sci. News 30 7 The magnetization [of a piece of iron] is the magnetic moment per unit volume, or the pole strength per unit cross-sectional area. 1962 D. R. Corson & P. Lorrain Introd. Electromagn. Fields v. 210 It is possible to generalize the concept of magnetic dipole moment to any distribution of current in space... For a current distribution J in a volume τ, m =..½∫r × Jdτ. 1970 G. K. Woodgate Elem. Atomic Struct. ix. 177 In order to be able to discuss departures of the nuclear charge distribution from spherical symmetry we should like to attribute to the nucleus electric multipole moments. 1992 S. P. Maran Astron. & Astrophysics Encycl. 597/2 When..the radiating charge is not a single point charge, physicists often describe the distribution of charges (or currents) in terms of a multipole expansion or moments of the charge (or current) distribution. < as lemmas |
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