| 释义 |
multipole, n. and a. Physics.|ˈmʌltɪpəʊl|
[f. multi- 2 + pole n.2]
A. n. A system of 2l monopoles (l = 1, 2, 3,{ddd}) with no net charge or pole strength and no moment of a lower order than l (cf. moment n. 8 c); the dipole (l = 1) is often treated as a special case and the quadrupole (l = 2) regarded as the multipole of lowest order. Freq. attrib. or as adj., esp. designating electromagnetic radiation of the kind produced by a multipole with a moment varying sinusoidally in magnitude.
In quot. 1916 this may not be the precise sense.
1916Jrnl. Amer. Chem. Soc. XXXVIII. 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. 1929Physical Rev. XXXIV. 1252 Since m must change by {pm} 1,..the transition j = 0→ j = 0 cannot occur for multipole radiation. 1932J. 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’. 1950D. Halliday Introd. Nucl. Physics ii. 57 If {vb}△I{vb} = 1 the multipole order is 2 and we have..a dipole transition; if {vb}△I{vb} = 2, the multipole order is 4 and we have a quadrupole transition. 1952Blatt & Weisskopf Theoret. Nucl. Physics xii. 586 The electric multipole fields have non-vanishing radial components of E, and the magnetic multipole fields have non-vanishing radial components of H. The angular momentum carried by one quantum of multipole radiation is ħl, with z component ħm. Electric and magnetic multipole radiation of order l, m carry the same angular momentum but differ through their parity. Ibid. 587 Any arbitrary field E(r), H(r) which obeys the free-space Maxwell equations can be expanded in terms of multipoles. 1962Corson & Lorrain Introd. Electromagn. Fields ii. 52 For the general multipole, characterized by the letter l, the potential varies as 1/rl+1. 1970[see moment n. 8 c].
B. adj. (Freq. written multi-pole.) Designed to close or open several circuits simultaneously.
1927Wireless World 22 June 786/3 It is sometimes recommended that a multi-pole switch should be fitted in order to switch off both batteries. 1934Pract. Wireless IV. 667/3 This multi-pole switch converts the usual panel-controlled push-pull action into a lateral movement. 1962G. A. T. Burdett Automatic Control Handbk. iii. 24 The multi-pole type of control switch is a double break changeover switch especially designed for the switching of squirrel-cage motors. |
