| 释义 |
reactance Electr.|riːˈæktəns|
[ad. F. réactance (É. Hospitalier 1893, in L'Industrie Électrique 10 May 210/1), f. réaction reaction: see -ance and cf. Eng. resistance, impedance.]
1. a. The non-resistive component of impedance, arising from the effect of inductance or capacitance or both and causing the current to be out of phase with the e.m.f. causing it. Cf. impedance.
1893Trans. Amer. Inst. Electr. Engineers X. 413 The term ‘impedance’ is suggested for the denominator..and for the quantity enclosed between the brackets, the term ‘reactance’ is proposed. 1896F. Bedell Princ. Transformer iv. 68 The reactance is, accordingly, equal to the component of the impressed electromotive force at right angles to the current, divided by the current. Reactance is measured in ohms. 1902W. G. Rhodes Alternating Currents 62 We propose to determine the equivalent resistance R, and the equivalent reactance S, of the combination. 1940Amateur Radio Handbk. (ed. 2) i. 10/2 The reactance of a condenser increases as the frequency of alternating current decreases... The reactance of an inductance decreases as the frequency decreases, which is the opposite effect to that of a condenser. 1970D. F. Shaw Introd. Electronics (ed. 2) ii. 33 The general definition of complex impedance is Z = R + jX, where R is the resistance and X is the reactance of the circuit. 1975D. G. Fink Electronics Engineers' Handbk. vii. 8 The reactance of a capacitor is given by Xc = 1/2πfC = 1/ωC (ohms) where f = ω/2π is the frequency in hertz.
b. = reactor 2 a.
1923Mod. Wireless I. 263 Try reversing the connections of the Armstrong inductance or reactance. 1947R. Lee Electronic Transformers & Circuits vi. 150 To avoid introducing losses and attenuation in the transmission bands, reactances as nearly pure as practicable are used in the elements of a wave filter. 1961[see reactor 2 a].
2. Mech. and Acoustics. The imaginary component of a mechanical or acoustic impedance, producing a phase difference between a driving force and the resulting motion but no dissipation of energy.
1925Physical Rev. XXV. 91 In the acoustic filters the impedances were combinations of the reactances, iMω and i/Cω, ω being 2π times the frequency, M the inertance and C the capacitance. 1932W. West Acoustical Engin. i. 3 Any impedance may be expressed as the vectorial sum of two components, a resistance and a reactance, whose phases differ by 90°. Ibid. iv. 54 The impedance comprises a resistance component, which depends on the rate of absorption of sound by the walls of the cavity..and an elastic reactance, in parallel, which depends on the volume of the cavity. 1950Kinsler & Frey Fund. Acoustics viii. 202 The acoustic reactance x of a sound medium..is the component that results from the effective mass and stiffness of the medium. 1958Condon & Odishaw Handbk. Physics ii. iii. 22/2 The reactance is the sum of the two contributions: -ik/ω, the elastic reactance, and iωm, the inertial reactance. 1968H. J. Pain Physics of Vibrations & Waves ii. 38 Mass, like inductance, produces a positive reactance, and the stiffness behaves in exactly the same way as the capacitance.
3. Psychol. A term sometimes used for the type of response aroused in a person who feels his freedom of choice is threatened or impeded.
1966J. W. Brehm Theory of Psychol. Reactance i. 2 Since this hypothetical motivational state is in response to the reduction (or threatened reduction) of one's potential for acting, and conceptually may be considered a counterforce, it will be called ‘psychological reactance’. 1970Jrnl. Personality & Social Psychol. XIV. 18 If the communication arouses reactance, the individual will tend to reject its position in order to demonstrate his freedom to decide for himself. 1972Harvard Law Review LXXXVI. 399 ‘Reactance’ is conceived to be an aversive state created in the individual by a threatened loss of his freedom to act or choose.
4. attrib. and Comb.
1921Wireless World IX. 187/1 Reactance coils are used in conjunction with valve sets. 1964R. F. Ficchi Electr. Interference x. 203 A reactance-grounded system is one in which a reactance is inserted in the connection to ground. 1967Electronics 6 Mar. 186/1 For slow scan applications, however, the reactance components would become excessively large and difficult to stabilize with temperature. 1972L. S. Wrightsman Social Psychol. in Seventies x. 306 Reactance theory concerns itself with situations where one's freedom of choice is threatened. 1976Tedeschi & Lindskold Social Psychol. viii. 360/1 Numerous experiments have shown reactance-like effects in the laboratory. Ibid. 361/1 Reactance studies in which subjects are told they are being evaluated for leadership. |