▪ I. phase, n.
(feɪz)
[ad. mod.L. phasis, a. Gr. ϕάσις: see phasis; = F. phase (Furetière a 1688), Sp., It. fase, Pg. phase, Ger. phase. In Eng. originally used in L. form phasis, pl. phasēs. The English use of phase appears to have arisen in the 19th c. from taking mod.L. pl. phasēs (which was more in use than the sing.) for an Eng. plural, and deducing from this a sing. phase; which would be natural to any one who knew that the French forms are phase, phases.
It results from this that phases is the written pl. both of phasis and of phase, and that in many instances it is not possible to say to which singular it is meant to belong.]
1. Each of the aspects or appearances presented by the moon or any planetary body, according to the amount of its illumination: = phasis 1.
Thus the crescent moon, half moon, gibbous moon, and full moon, are phases; but the term is commonly applied to the points of new moon, first quarter, full moon, and last quarter.
| 1812 Woodhouse Astron. xxx. 295 The period of the Moon's phases. Ibid. xxxv. 350 To the greatest phase, that is, to the greatest quantity of the eclipsed disk. 1854 Moseley Astron. lxii. (ed. 4) 187 All those varieties of phase which characterize the changes of the moon. 1868 Lockyer Elem. Astron. iii. §229 Let us now explain what are called the phases of the Moon. |
2. a. Any one aspect of a thing of varying aspects; a state or stage of change or development;
= phasis 2. Esp. in
phr. phase one (or
phase two, etc.): the first (or second, etc.) planned stage of a process, series of events, etc.
| 1841 Catlin N. Amer. Ind. I. x. 78 These clay-formed hills..are..subjected to continual phases, more or less, until ultimately their decomposition ceases. 1843 Lytton Last Bar. iii. ii, He saw her in the most attractive phase of her character. a 1862 Buckle Civiliz. III. iii. 190 Unfolding the successive phases of their mighty career. 1875 Jowett Plato (ed. 2) IV. 226 To enter into each successive phase of the discussion which turns up. 1883 Leifchild in Contemp. Rev. XLIII. 54 Shakespeare has painted every phase of antagonism to the world. 1957 Economist 5 Oct. 24/2 There was little..to suggest that the government expects Britain to be a very active combatant in ‘Phase Two’ of another war. Mr. Butler's emphasis was solely on Phase One. 1974 Times 1 Apr. 21/1 A contract..for phase one of a new district general hospital. 1977 Whitaker's Almanack 1978 580/1 The Chancellor of the Exchequer, other ministers, and the T.U.C. economic committee opened negotiations for a Phase 3 pay policy. |
b. Zool. A particular period of an animal's life, distinguished by a characteristic form, colour, or type of behaviour. Also
attrib.| 1873 [see form-genus (form n. 22)]. 1921 B. P. Uvarov in Bull. Entomol. Res. XII. 153 We are yet far from knowing whether the transformation of one form [of locust] into the other is due to some immediate external influence or to some yet unknown internal cause; I think therefore, that the term ‘phase’..suggested to me by Dr. G. A. K. Marshall is more appropriate [than ‘morpha’]. Ibid. 155 The swarming phases [of locusts] enable the species to extend at one stroke its area of distribution. 1937 Ann. Reg. 1936 54 Phase variation was found in grasshoppers. 1947 New Biol. III. 10 It is now a recognised fact that all true locusts occur in two phases—the solitary and the swarming, or gregarious as it is usually called. 1956 Nature 28 Jan. 167/2 Dr. M. L. Roonwal's work has been concerned..with phase-transformation and population dynamics of the desert locust. 1964 L. S. Crandall Managem. Wild Mammals in Captivity 368 It [sc. the jaguarundi]..occurs in two color phases, dark gray and reddish brown. 1966 B. P. Uvarov Grasshoppers & Locusts I. 386 The ideas behind the phase theory are being followed by workers on other insects. 1973 Nature 24 Aug. 484/1 Phase transformation in locusts refers to the changes induced when solitary hoppers (juvenile locusts) become gregarious. 1977 Times 18 Aug. 14/5 A slate-black falcon..was agreed to have all the field-clues of the dark phase of Eleanora's falcon, one of Europe's rarest predators. |
c. A temporarily difficult or unhappy period or stage of development,
esp. of adolescents;
freq. in
to go (or pass) through a phase.
| 1913 W. J. Locke Stella Maris xix. 258 ‘What's the matter with her, for pity's sake?’ asked Herold... ‘Perhaps it's a phase. Young girls often pass through it.’ 1932 R. Lehmann Invitation to Waltz i. ii. 27 Mrs. Curtis was silent: a pregnant silence. Kate was going through a phase. Best not to take too much notice. 1960 Times 28 May 7/4 ‘It's only a phase’, we say uncertainly when our children sulk, fight, or burst into tears for no reason. 1971 [see crowd n.3 2 c]. 1971 H. McCloy Question of Time i. iii. 36 Whenever Pel or Mél get into trouble, Mrs Heron always says: ‘It's just a phase they're going through.’ |
3. a. Physics. A particular stage or point in a recurring sequence of movements or changes,
e.g. a vibration or undulation, considered in relation to a particular reference position or time. Also
transf. in phase, in the same phase; having the same phase at the same time;
const. with;
out of phase, not in phase.
| 1861 Phil. Mag. XXI. 163 Two series of undulations traversing the same space do not combine into one resultant as two attractions do, but produce an effect depending on relations of phase as well as intensity. 1863 E. Atkinson tr. Ganot's Elem. Treat. Physics vii. viii. 474 Fig. 362 represents two waves issuing from the same source of light, and meeting at a, under a very acute angle in the same phases [ed. 2 (1866): in the same phase], while fig. 363 represents the coincidence of two waves in opposite phases of undulation. 1874 Spottiswoode Polaris. Lt. iii. 32 The distance whereby one set of waves is in advance of another is called the difference of phase. 1875 Encycl. Brit. I. 101/2 Two particles which are in the same stage of vibration..and are moving in the same direction and with equal velocities, are said to be in the same phase. 1879 Thomson & Tait Nat. Phil. I. i. §54 The Phase of a simple harmonic motion at any instant is the fraction of the whole period which has elapsed since the moving point last passed through its middle position in the positive direction. 1891 J. W. Urquhart Dynamo Construction xvi. 239 If switched when not ‘in phase’, the fresh machine would..be quickly pulled into unison. 1892 Lightning Spec. Suppl. 3 Mar. Gloss. Electr. Terms s.v., The phase of an alternating current or electro-motive force, is the proportion of the whole period which has elapsed since last alternating into the direction considered positive. 1903 T. Sewell Elem. Electr. Engin. (ed. 2) xvii. 337 The current flowing in the circuit, whether it be in or out of phase with the e.m.f., is indicated by the ammeter. 1931 Moyer & Wostrel Radio Handbk. ii. 74 In a circuit containing only non-inductive resistance the current and voltage are in phase. 1936 L. S. Palmer Wireless Engin. x. 403 The plate and outer grid may be indirectly connected by any device..which changes the phase of the output with respect to the input by 180°. 1953 Economist 14 Nov. 505/2 To keep the supply of raw materials in phase with productive capacity. 1973 Sci. Amer. June 47 The light is reflected from a system of mirrors and arrives either in phase or out of phase at the second Kerr cell, depending on the length of the light path between the cells. |
b. Electr. Engin. Each of the windings of a polyphase machine.
| 1904 M. B. Field in M. Maclean Mod. Electr. Pract. II. i. vi. 28 If one of the phases of a △-connected system is disconnected, the remaining two can still supply a three-phase current, but with a diminished efficiency. 1931 G. C. Blalock Princ. Electr. Engin. xviii. 243 The power in any polyphase circuit must of necessity be the sum of the powers in the component phases. It is usually more convenient, however, to determine polyphase power in terms of line voltage and current. 1962 Newnes Conc. Encycl. Electr. Engin. 787/2 The phases are interlinked in star connection. 1972 Smith & Hosie Basic Electr. Engin. Sci. ix. 244 Symmetrical delta-connected systems... The power developed in the generator, when supplying a balanced load, is three times that developed in each phase. Ibid. 254 Each phase of a 3-ph star-connected load is a coil of resistance 20 Ω. |
4. A physically distinct and homogeneous form of matter that may be present in a system, characterized by its composition and state and when present separated by a bounding surface from other forms.
| 1875 J. W. Gibbs in Trans. Connecticut Acad. III. 152 We may call such bodies as differ in composition or state, different phases of the matter considered, regarding all bodies which differ only in quantity and form as different examples of the same phase. 1916 C. A. Edwards Physico-Chem. Properties of Steel iv. 47 From the phase rule we know that three phases can coexist in equilibrium, in a binary system, only at one temperature. At the Ar1 point there are three phases—namely, α-iron, carbide of iron, and the solid solution of the eutectoid composition. 1931 Maass & Steacie Introd. Princ. Physical Chem. ix. 135 Every liquid has a vapour pressure and will evaporate and enter the gas phase. 1967 J. Wilks Properties of Liquid & Solid Helium i. 6 Both solid 3He and 4He exist in three phases with different crystal structures. 1971 I. G. Gass et al. Understanding Earth iii. 55/1 These two phases, sand and clay, are very effectively separated from each other by deposition or sedimentation from water. |
5. attrib. and
Comb., as (sense 3)
phase difference,
phase doctrine,
phase relation(ship),
phase reversal;
phase-sensitive adj.; (sense 4)
phase boundary;
phase advancer Electr. Engin., a device for improving the power factor of an induction motor by generating a magnetizing current in the rotor circuit which leads the main rotor current in phase;
phase change, a change in the phase of a wave (
phase 3) or of a substance (
phase n. 4);
phase changer Electr. Engin. = phase converter;
phase contrast, the technique in microscopy of introducing a phase difference between parts of the light supplied by the condenser so that interference causes the outlines of the sample, or the boundaries between parts of differing optical density, to appear more prominent;
usu. attrib.,
esp. in
phase-contrast microscope,
phase microscopy;
phase converter,
convertor Electr. Engin., a device which converts an alternating current into one having a different number of phases but the same frequency;
phase diagram Chem., a diagram which represents the limits of stability of the various phases of a chemical system at equilibrium with respect to two or more variables (commonly composition and temperature); an equilibrium diagram;
phase displacement Electr., a difference in phase;
phase distortion, distortion of a waveform caused by components of different frequencies being propagated at different speeds, so that their phase relations are altered;
phase inverter,
invertor Electr., a phase splitter which produces two signals 180 degrees out of phase;
phase-lock n. Electronics, the stabilization of the frequency of an oscillator with respect to that of another, stable, oscillator of lower frequency, by means of a circuit in which any variation in the higher frequency generates a phase difference which produces an automatic correction to that oscillation;
freq. attrib.; so
phase-lock v. trans., to stabilize (an oscillation or a device) in this way;
phase-locked ppl. a.,
-locking vbl. n.;
phase microscope Biol., a phase-contrast microscope; so
phase microscopy;
phase modulation Telecommunications, modulation of a wave by variation of its phase; hence
phase-modulated ppl. a., (as a back-formation)
phase-modulate v. trans.;
phase reaction Chem., a chemical or physical change which involves the transfer of material between phases, or the appearance or disappearance of a phase;
phase rotation Electr. Engin. = phase sequence 1;
phase rule,
Phase Rule Physical Chem. (see
quots. 1913, 1966);
phase separation Physical Chem., the separation of one phase into two,
esp. the separation of a mixture by partition between two phases, or the coacervation of a colloidal solution;
phase shift, a change in the phase of a waveform;
phase-shifter Electr., a circuit or device which introduces a change in the phase of an oscillation;
orig. spec. a transformer which alters the power factor in an a.c. circuit by changing the phase relationship of voltage and current; so
phase-shifted,
-shifting,
ppl. adjs.;
phase space Physics, a multi-dimensional space in which each axis corresponds to one of the co-ordinates (spatial or other) required to specify the state of a physical system, all the co-ordinates being thus represented so that a point in the space corresponds to a state of the system;
phase-splitter Electr., a circuit or device which splits a single-phase voltage into two or more voltages differing in phase; so
phase-splitting ppl. a. and vbl. n.;
phase transition, a change in the phase of a substance (
phase n. 4);
phase velocity, the speed of propagation of a sine wave or a sinusoidal component of a complex wave, equal to the product of its wavelength and frequency (
cf. group velocity);
phase-wound a. Electr. Engin., having a secondary in the form of windings rather than a squirrel-cage.
| 1909 M. Walker in Jrnl. Inst. Electr. Engin. XLII. 611 The author believes that it is possible to devise a new type of machine to act as an exciter in the manner proposed by M. Leblanc... Such a machine might be called a ‘phase advancer’. 1920 Whittaker's Electr. Engineer's Pocket-bk. (ed. 4) 521 Should the speed be increased above synchronism, the reactance attains a negative value (i.e. the phase-advancer acts as a capacity), with the result that the current is advanced and the leading component of it compensates for the magnetizing current of the induction motor, thereby relieving the system. 1962 Newnes Conc. Encycl. Electr. Engin. 596/1 Many different types of phase advancer have been developed but they are only rarely used because of the high maintenance required. |
| 1952 New Biol. XII. 99 The adsorption of simple organic molecules from the atmosphere or from solutions at the surface of phase boundaries may have been of far greater importance. Suitable phase boundaries occur..at the surface of crystals of inorganic minerals. |
| 1914 Physical Rev. III. 126 At high pressures we are concerned with phase changes of only two types, from the fluid to the solid (or crystalline) phase, and from one solid phase to another. Ibid. 354 Methods..for determining the phase change produced by reflection from the surfaces of metals. 1956 Nature 4 Feb. 240/1 The rate of diffusion in the plane of the layers for each phase-change is equal in all directions. 1962 A. Nisbett Technique Sound Studio 254 Noise..is strongly discriminated against [by frequency modulation], though it does produce phase-change effects which cannot be eradicated. 1974 Times 4 Feb. 14 It was once thought that deep earthquakes marked the simultaneous collapse of many cubic kilometres of rock from one atomic structure to another—a so-called phase change. |
| 1900 Jrnl. Electr., Power & Gas Oct. 81/2 (heading) An induction motor phase changer. 1935 Discovery Nov. 326/1 Phase changers and automatic regulators have worked perfectly [in locomotives of Hungarian railways]. |
| 1934 F. Zernike in Monthly Notices R. Astron. Soc. XCIV. 377 (heading) Diffraction theory of the knife-edge test and its improved form, the phase-contrast method. 1942 Jrnl. Sci. Instrum. XIX. 71 (heading) Phase-contrast microscopy. 1947 Nature 21 June 829/2 Mr. Taylor has made and described a new phase-contrast microscope in which a controlled variable amplitude for the ‘direct-light’ component is obtained. 1961 M. Fran{cced}on Progress in Microsc. ii. 65 Originally used by its inventor [sc. Zernike] for inspecting telescope mirrors, the phase contrast technique was applied to microscopy shortly afterwards. 1966 McGraw-Hill Encycl. Sci. & Technol. VIII. 399/2 The phase contrast microscope is the routine instrument for the examination of living cells. 1970 E. M. Slayter Optical Methods in Biol. xiii. 288 The phase contrast microscope is a device which renders differences in refractive index between regions of a specimen visible as differences in intensity. 1971 Nature 17 Sept. 198/1 Parasitaemia was estimated by examination of fresh blood preparations by phase contrast microscopy..every 2–3 days. Ibid. 26 Nov. 227/2 Cytological characters and chromosomal behaviour during mitosis were studied in live cultures under phase contrast. |
| 1916 Trans. Amer. Inst. Electr. Engin. XXXV. 1318 No. 4 is in general respects the same as No. 2 with the addition of a relatively new development known as the ‘phase converter’ which preserves the balance of the system even when large blocks of single-phase power are taken from the system. 1935 Discovery Nov. 326/1 The phase converter is usually regarded as the most complicated part of the locomotive. 1967 C. V. Jones Unified Theory Electr. Machines xviii. 241 As a final example of induction motor performance, its operation as a phase converter will be briefly considered. |
| 1911 Chem. Abstr. V. 1219 (heading) Phase diagram of silver iodide. 1926 Jrnl. Iron & Steel Inst. CXIII. 655 The phase diagram is characterised by a solid solution of tin in iron with a maximum of 18 per cent tin, and by two compounds. 1972 McGraw-Hill Yearbk. Sci. & Technol. 350/2 The most apparent departure from conventional behavior is seen in the phase diagram of solid He3 shown in Fig. 2. |
| 1889 J. A. Fleming Alternate Current Transformer I. iv. 291 θ is the angle of phase difference of the currents. 1962 Symp. Zool. Soc. No. 7. 10 It has been generally supposed until recently that for man..phase differences are of no account. But we now realize that if changes of phase of particular components occur at a sufficiently rapid state, then differences of sound-quality are in fact heard. |
| 1907 H. H. Norris Introd. Study Electr. Engin. iv. 120 (heading) Phase displacement of alternating quantities. 1933 Phase displacement [see balanced ppl. a. 6]. |
| 1928 Bell Syst. Techn. Jrnl. VII. 195 For relatively short distances the deleterious effects of phase distortion are not appreciable. 1961 G. Millerson Technique Television Production iii. 43 Certain video distortions, from phase-distortion to signal reflections, can also be the reason for poor definition in a picture. 1970 J. Earl Tuners & Amplifiers ii. 43 For high quality all the significant sideband signals must be handled by the i.f. channel to avoid phase distortion and treble attenuation. |
| 1904 Westm. Gaz. 23 Apr. 12/2 Roozeboom, who applied the phase doctrine to all kinds of equilibrium, is the founder of a new branch of physical chemistry. |
| 1942 A. Hund Frequency Modulation xi. 178 Figure 49 shows a balanced reactance-tube modulator where a phase inverter replaces the push-pull input transformer. 1951 Electronic Engin. XXIII. 64 Phase-invertors using resistance-loaded triode valves are well known. 1960 E. N. Lurch Fund. Electronics xv. 353 A circuit arrangement to produce balanced voltages which are 180° out of phase for the grids of the push-pull stage is termed a phase inverter. |
| 1953 W. A. Edson Vacuum-Tube Oscillators xiv. 342 The question of time delay or phase lock arises in all methods of frequency composition. 1957 Electronic & Radio Engineer XXXIV. 141/2 The simple phase-lock loop is effectively a position control servo-mechanism operated by a d.c. error voltage from the phase-sensitive detector. 1973 Wireless World Dec. 605/1 The device contains a phase-locked loop which I have found suitable for demodulating teleprinter f.s.k. signals because it requires only a small input signal for phase lock. 1974 Harvey & Bohlman Stereo F.M. Radio Handbk. iv. 65 When ‘phase-lock’ is achieved the in-phase detector registers this by providing a d.c. output. |
| 1955 Proc. IRE XLIII. 869/1 A circuit has been developed with which microwave oscillators may be phase-locked to weak but stable reference signals. 1967 Electronics 6 Mar. 6/2 (Advt.), The generator frequency can be phaselocked to an external standard frequency. |
| 1959 Proc. IRE XLVII. 1137/2 A phase-locked oscillator can serve as a filter of arbitrarily narrow bandwidth. 1976 Gramophone Aug. 354/2 A quartz crystal controlled phase-locked servo circuit holds speed drift within 0.002% and is independent of any changes in line voltage or frequency. |
| 1955 Proc. IRE XLIII. 872/2 This phase-locking circuitry may also be used to make a divider of particular use in the microwave region where no other kind exists. 1963 Electronics 19 Apr. 45/2 Because phase-locking is used, the offset between channels is affected only by the frequencies assigned to the i-f reference oscillators. 1977 Proc. R. Soc. Med. LXX. 379/2 Temporal information depends on phase-locking; the nerves fire at a particular phase of the stimulating wave-form so that for sinusoids the time intervals between firings are approximately integral multiples of the period of the wave-form. |
| 1946 Trans. Amer. Microsc. Soc. LXV. 129 (heading) Phase microscopy. Ibid., The Phase Microscope reveals detail in transparent materials having regions of slightly differing absorption or with different indices of refraction. 1949 World-Herald (Omaha, Nebraska) 4 Dec. 19–a, The phase microscope can see the interior of a cell in bright or dark contrast to bring hidden parts into view. 1964 N. S. Cohn Elem. Cytol. ii. 22 The observation of living cells has been greatly facilitated by the development of phase microscopy and related optical systems. 1970 O. W. Richards in J. E. Blair et al. Man. Clin. Microbiol. 24/1 The phase microscope has an annular stop in the condenser to limit the lighting to a symmetrical hollow cone. |
| 1930 Proc. IRE XVIII. 633 (heading) The effect of frequency or ‘phase’ modulation upon signal quality. 1936 Phase-modulated [see frequency-modulated ppl. a.]. 1941 Electronic Engin. XIV. 537/3 Phase modulation possesses much the same advantages as frequency modulation. Signal-to-noise ratio is greater than for amplitude modulation..though it is less than for frequency modulation since the triangular noise spectrum effect is absent because noise itself phase modulates the carrier. 1962 J. H. & P. J. Reyner Radio Communication iii. 140 Whereas with phase modulation the modulation index m is simply proportional to the amplitude of the modulating signal, with frequency modulation it is also inversely proportional to the modulation frequency. 1968 B. P. Lathi Communication Syst. iv. 213 If we integrate the modulatory signal f(t) first and then allow it to phase-modulate the carrier, we obtain a frequency-modulated carrier. 1974 Harvey & Bohlman Stereo F.M. Radio Handbk. ii. 36 It is a characteristic of phase modulation that the amount of frequency swing introduced is proportional not only to the amplitude of the modulating signal but also to its frequency. 1976 Sci. Amer. June 62/3 The antenna transmits a phase-modulated radio signal that carries scientific and engineering data from the spacecraft to the radio tracking stations on the earth. |
| 1920 D. A. Clibbens Princ. Phase Theory i. 3 If the temperature is raised,..a transference of material from one phase to another will, in general, occur; such a transference is known as a phase reaction. 1923 A. C. D. Rivett Phase Rule iv. 72 Until the temperature reaches that of x1,..cooling does not bring about any phase reaction. 1938 S. T. Bowden Phase Rule & Phase Reactions i. 6 A phase reaction is a physical or chemical change which involves the appearance or disappearance of a phase. |
| 1878 Proc. R. Soc. Edin. IX. 604 They may be so related in phase that at one of the instants of maximum pressure of one of the constituents there is also maximum pressure of the other constituent. The same phase-relation, if the harmonic numbers of the constituent tones be odd, will give also coincident minimums. 1896 S. P. Thompson Dynamo-Electr. Machinery (ed. 5) xxvi. 708 (heading) Phase-relations in transformers. 1962 A. Nisbett Technique Sound Studio xii. 218 The phase relationship between the sounds. |
| 1898 Daily News 12 May 6/3 The features of Mr. Wood's phase reversal and silver zone plates. 1938 Science 4 Mar. 213/2 [They] misinterpret the situation still more by referring to.. the setting of gelatine as involving phase-reversal. 1957 Practical Wireless XXXIII. 539/2 There is a phase reversal across the common emitter circuit. 1962 A. Nisbett Technique Sound Studio 244 Cardioid microphone, microphone with a heart-shaped polar diagram (arrived at by adding omnidirectional and figure-of-eight responses together, taking into account the phase reversal at the back of the latter). |
| 1918 K. Edgcumbe Industr. Electr. Measuring Instruments (ed. 2) 254 The direction of phase rotation of the secondary pressures and currents may conveniently be checked by a phase rotation indicator. 1922 [see phased ppl. a. 1]. 1962 Newnes Conc. Encycl. Electr. Engin. 572/2 A simple portable instrument to indicate phase rotation. |
| 1896 Jrnl. Chem. Soc. LXX. ii. 415 Only at some one definite temperature would all four salts tend to coexist in an unchanged condition. This point is, in the case of solutions of the salts, a sextuple point in the sense of the phase rule. 1904 A. Findlay (title) The Phase Rule and its Applications. 1913 Bloxam & Lewis Bloxam's Chem. (ed. 10) 338 The Phase Rule of Willard Gibbs..is expressed in the equation P + F = C + 2,..where P is the number of phases, F the number of degrees of freedom, and C the number of components. 1935 Discovery Sept. 258/2 A system so complex as to baffle the most ardent exponent of the phase rule. 1966 McGraw-Hill Encycl. Sci. & Technol. V. 55/1 If a system consists of P phases and C distinguishable components, there are C + 2 thermodynamic variables (C chemical potentials µi, plus the temperature and pressure) which are interrelated by an equation for each phase. Since there are P independent equations relating the C + 2 variables, one needs to fix only F = C + 2 - P variables to define completely the state of the system at equilibrium; the other variables are then beyond control. This relation for the number of degrees of freedom F, or variance, is called the Phase Rule and was first derived by Willard Gibbs in 1873. |
| 1957 Phase-sensitive [see phase-lock n. above]. 1963 B. Fozard Instrumentation Nucl. Reactors xi. 135 This requires the provision of a phase-sensitive rectifier at the output. |
| 1941 Nature 27 Sept. 373/1 We have sought to replace the customary phase separation of ‘crude carotene’ and xanthophylls by using the same chromatographic technique for the removal of xanthophylls as well as of non-carotene chromogens from the petrol ether solution. 1947 Jrnl. Polymer Sci. II. 90 The phase separation in solutions of high polymers in the same solvent (technically known as incompatibility) has been studied for fourteen high polymers..dissolved in thirteen solvents. 1948 [see hæm, heme b]. 1960 P. A. Albertson Partition of Cell Particles ii. 13 Bungenberg de Jong & Kruyt..coined the term ‘coacervation’ for the general phenomenon of phase separation of colloid mixtures. 1970 [see coacervation 3]. 1971 Materials & Technol. II. vi. 340 Devitrification of glass is the formation of crystals (phase separation) in a glass. |
| 1927 Wireless World 1 June 686/2 In order to give a high-grade telephone line such an extended characteristic, special equipment for the equalisation of attenuation and of phase shift had to be devised. 1929 J. A. Ratcliffe Physical Princ. Wireless iii. 37 If a beam of light is focussed on to a point and then allowed to spread out on the other side of the focus, the total phase-shift is π. 1960 Practical Wireless XXXVI. 411/2 While a simple phase-shift oscillator..may be used coupled into a suitable amplifier installation, a neater method is to build the complete practice set together with power supply, speaker and controls into a self⁓contained unit. 1976 Gramophone Feb. 1398/1 Either we must accept some loss of loudness of rearward sources in mono playback, or a certain amount of phase-shift between the signals coming from the two loudspeakers in stereo. |
| 1965 Wireless World Aug. 396/2 If the gate voltage is phase-shifted with respect to the anode voltage, the firing point is delayed by the appropriate time. |
| 1908 Electrician 11 Dec. 341/2 In Fig. 1, which shows diagrammatically a phase shifter for a two-phase supply, AB and CD are the terminals of the two phases. 1951 Engineering 23 Feb. 221/2 The first method enables the point in each cycle at which the anodes become conducting to be delayed..by a double-wound phase-shifter. 1959 K. Henney Radio Engin. Handbk. (ed. 5) xiv. 16 In the microwave region, a matched transmission line or slotted line may be used as a phase shifter. |
| 1908 Electrician 11 Dec. 341/1 (heading) The use of a phase-shifting transformer for wattmeter and supply meter testing. 1929 Phil. Mag. VIII. 168 Thus the artificial line has zero attenuation at all frequencies, and is a pure phase⁓shifting network. 1965 Wireless World July 332/1 Thin film circuits..may be more useful where passive networks only are required—for attenuators, RC phase shifting networks, etc. |
| 1927 R. C. Tolman Statistical Mech. iii. 32 To follow the behavior of such a system..it is very convenient to think of its phase as given by the position of a representative point..in a 2m-dimensional space (phase space) corresponding to the 2m coordinates and momenta whose values are to be specified. 1970 G. K. Woodgate Elem. Atomic Struct. vi. 98 The exclusion principle states, in this context, that not more than two electrons are allowed in each volume of size h3 in phase space. 1974 G. Reece tr. Hund's Hist. Quantum Theory vi. 80 Ehrenfest attempted to interpret the radiation formulae by means of a weight function in phase space. |
| 1896 D. C. & J. P. Jackson Alternating Currents 652 Special starting devices must be included in the design and construction [of single-phase induction motors]. As a rule, this takes the form of what is called a Phase Splitter. 1965 Wireless World Aug. 72 (Advt.), A pentode triode ideally suited for use as a voltage amplifier and phase splitter. 1970 J. Earl Tuners & Amplifiers ii. 54 The collector and emitter outputs..are equal in amplitude but opposite in phase, rather like the signals from a simple valve phase-splitter circuit. |
| 1895 S. P. Thompson Polyphase Electric Currents iv. 99 (caption) Phase-splitting device. 1947 Wireless World Aug. 274/1 The advantages of resistance-capacitance circuits for phase-splitting in push-pull amplifiers are now well recognized. 1969 R. W. Smeaton Motor Applic. & Maintenance Handbk. xviii. 14 A simple phase-splitting device could be rigged up..so that the motors could be used on 120 volts, 60 cycles, single-phase. 1975 G. J. King Audio Handbk. iv. 84 Some form of ‘phase-splitting’ stage is necessary to drive common-pair output stages. |
| 1939 Jrnl. Chem. Physics VII. 1019/1 A first-order phase transition. 1968 R. A. Lyttleton Mysteries Solar Syst. ii. 71 L is the energy per unit mass required for the phase-transition from solid to liquid. 1977 A. Hallam Planet Earth 11 Such a phase transition does not involve differences in chemical composition but only a spatial rearrangement of the atoms in the silicate structure. |
| 1932 Ladner & Stoner Short Wave Wireless Communication iii. 34 For the case of a group of waves passing through an ionised medium, therefore, the phase velocity will be greater than c, the velocity of light in a pure dielectric,..but the group velocity will be less than c. 1968 M. S. Livingston Particle Physics iii. 49 Consider a pulse of water waves originating from the point where a stone strikes the water, and focus on a particular wave crest... The velocity with which the general disturbance moves is the group velocity; the velocity of the wave crest relative to the water is the phase velocity. |
| 1907 H. H. Norris Introd. Study Electr. Engin. x. 290 The phase-wound motor has very satisfactory starting qualities and draws little excess starting current. |
▪ II. phase obs. erron. form of
pasch,
pace n.2; an error in various Dicts. (Webster 1828–64, etc.) for
prase,
Min.▪ III. phase erroneous spelling of
faze v., to discompose, disturb.
| 1889 ‘Mark Twain’ Yankee at Crt. K. Arthur (Tauchn.) II. 154 His spirit—why, it wasn't even phased. 1898 R. B. Townshend in Westm. Gaz. 19 Nov. 2/1 It don't seem to ‘phase’ him in the very slightest. |
▪ IV. phase, v. (
feɪz)
[f. the n.] I. 1. trans. To adjust the phase of; to bring into phase, synchronize.
| 1938 A. E. Greenlees Amplification & Distribution of Sound x. 154 Wherever two or more loudspeakers are used, these must be properly phased so that all the diaphragms move in the same direction at the same time. 1951 S. Deutsch Theory & Design Television Receivers xvi. 502 A phasing control is needed in order to phase the oscilloscope sweep so that the beam goes from left to right when the sweep frequency goes from its lowest to highest extremes. 1967 Electronics 6 Mar. 67/2 Researchers have succeeded in phasing the lasers. 1970 J. Earl Tuners & Amplifiers vi. 131 The two speakers of a stereo pair..can be correctly phased initially with little danger of the phasing being upset subsequently. 1974 Sci. Amer. Jan. 118/2 One can also ‘phase’ the drum and the mirror by interrupting the circuit of the drum motor momentarily. |
2. To organize or carry out gradually in planned stages or instalments.
| 1949 [implied in phased ppl. a. 2]. 1955 Bull. Atomic Sci. Jan. 9/3 The British-French proposals were directed primarily to the problem of phasing the controls. 1963 Ann. Reg. 1962 97 The British members of the Commission preferred a merger phased over five years. 1969 Daily Tel. 8 Jan. 22/7 New tenants will face rent increases of as much as {pstlg}1 a week, while increases will be phased over three years for existing tenants. |
II. With adverbs:
3. phase down: to reduce or decrease (something) gradually or in planned stages.
| 1970 Times 6 Nov. 8 The secretary said that the programme to phase down American operations in Indo-China..‘is solidly based’. 1972 Physics Bull. Feb. 76/1 If the innovation manager is truly perceptive, he can phase down his work without human suffering. 1974 Daily Tel. 11 Feb. 2/8 Production had been cut to 60 per cent of normal. It would be phased down further for two months, when virtually no steel would be produced. |
4. phase in.
a. intr. To come into phase.
rare.
| 1929 Proc. IRE XVII. 1787 The separate multiple echoes from a given set of pulses phase in and out at different rates... Part of the observed phasing must be due to changes in optical path. |
b. trans. To introduce or incorporate (something) gradually or in planned stages. Also
intr., to be so introduced.
| 1955 Bull. Atomic Sci. Feb. 57 New weapons must be ‘phased in’ gradually to our existing weapons systems. 1959 Time 9 Feb. 11 It would be dangerous to phase out obsolescent weapons too slowly. But it would be exceedingly wasteful to phase in too heavily the newer weapons. 1971 Farmer & Stockbreeder 23 Feb. 7/3 The levies should be phased in over a one-year period. 1972 [see sense 5 d below]. a 1974 R. Crossman Diaries (1976) II. 472 As for national superannuation, we shouldn't try and bring it forward but phase it in in 1975, when a large number of existing pensioners will be dying off. |
5. phase out.
† a. Electr. Engin. To eliminate phase differences between (parts of polyphase equipment that are to be connected together).
Obs.| 1921 W. S. Ibbetson Motor & Dynamo Control viii. 283 The synchronising of two- and three-phase generators may be performed by connecting the synchronising lamps across one phase only, provided the alternators are correctly connected up to the bus bars. To phase out such connections before a machine may be paralleled the following operations may be performed. 1939 ― Electric Power Engineers' Handbk. vi. 151 If the leads were not correctly phased out so that the phases of all the machines were in the same sequence, interchange of current between the alternators would occur. |
b. To eliminate by adjustments of phase.
nonce-use.
| 1921 Wireless World 6 Aug. 287/2 The interfering note can be completely ‘phased out’ by adjusting bellows and tube to equal length. |
c. intr. To become out of phase.
rare.
d. trans. To remove, eliminate, or take out
of gradually or in planned stages. Also
intr., to disappear gradually.
| 1954 Quartermaster Rev. July–Aug. 159/1 We in Defense are phasing out the support of basic research for the general welfare. 1955 Sun (Baltimore) (B ed.) 25 Apr. 8/5 The old propellor-driven Mustangs..will be ‘phased out’ on August 1—which means that replacement parts will have become so scarce that they cannot longer be operated in safety. 1959 [see sense 4 b above]. 1959 New Scientist 17 Sept. 446/2 Finding a way to phase out the jet lift as forward speed generates lift in the wings. 1967 Guardian 9 Jan. 6/4 We could safely decide to phase out the carrier fleet by 1970. 1969 J. Gardner Compl. State of Death ix. 172 It's been a tricky job phasing out these people. 1969 Daily Tel. 13 Dec. 13/1 While he was ‘phasing out’ from the public view, he said, he was not shirking his duties as an MP. 1970 Ibid. 30 Sept. 1/6 The Jaguar 420G range of cars is to be gradually phased out of production. 1971 Nature 1 Oct. 299/1 Five top level scientific committees..have recommended that the pesticide be phased out of domestic use. 1972 Lebende Sprachen XVII. 135/1 In a research organization projects do phase in and phase out all the time. 1975 Times 22 Sept. 3/3 The Government wants to phase out pay beds. 1977 B. Pym Quartet in Autumn xii. 102 The whole department was being phased out and only being kept on until the men working in it reached retirement age. 1979 Time 2 Apr. 59/1 It has been generally thought that Ford would start phasing out after Sept. 4, 1980, when he turns 63. |
† 6. phase up Electr. Engin.: to synchronize, bring into phase.
Obs. rare.
| 1904 W. R. Bowker Dynamo, Motor & Switchboard Circuits v. 99 In connecting two-phase generators for parallel running it is necessary to synchronise both phases the first time the machines are paralleled. After they have once been ‘phased-up’ synchronising one phase is sufficient. Fig. 101 shows the connections for properly ‘phasing up’ two two-phase generators. |