| 释义 |
amplitude|ˈæmplɪtjuːd|
[a. Fr. amplitude, ad. L. amplitūdo, -inem, breadth, f. ampl-us: see ample and -tude.]
The quality of being ample.
1. Extension in space, extent, largeness; chiefly, width, breadth.
1599Nashe Lenten Stuffe (1871) 81 It cuts out an Island of some amplitude. 1671Grew Anat. Plants i. i. (1682) 9 Growing to a three-four-five-fold amplitude above their primitive size. 1823Lamb Elia Ser. i. xv. (1865) 121 An amplitude of form and stature, answering to her mind. 1833Chalmers Constit. Man. (1835) I. v. 208 Throughout the amplitudes of savage and solitary nature.
2. Of things immaterial: width, breadth, fullness; copiousness, abundance.
1605Bacon Adv. Learn. ii. §2 (1873) 76 All works are overcommen by amplitude of reward..and by the conjunction of labours. 1664H. More Myst. Iniq. 248 The amplitude of that Jurisdiction to which they belong. 1794Paley Nat. Theol. xxvi. (1879) 412 It is in those things..that the amplitude of the Divine benignity is perceived. 1850Lynch Theoph. Trin. viii. 138 The blue of day shall image for us the amplitude of the divine charity. 1864Sat. Rev. 31 Dec. 813/2 [He] arrays all the facts before the reader in their original amplitude.
3. Of mental capacity: breadth, wide range.
1575Laneham Let. (1871) 48 Az for the Amplitude of his Lordship's mynde. a1652J. Smith Select Disc. ix. iii. (1821) 423 Religion..does work the soul into a true and divine amplitude. 1746Hervey Medit. & Contempl. (1818) 139 The amplitude of a generous heart. 1814Cary Dante, Par. x. 110 Endowed With sapience so profound..That with a ken of such wide amplitude No second hath arisen. 1828Macaulay Hallam, Ess. I. 52 His mind is..distinguished by the amplitude of its grasp.
4. Excellence, dignity, grandeur, splendour.
1549Compl. Scotl. 2 Ȝour honorabil amplitude of verteouse dignite incressis daly. 1655Fuller Ch. Hist. i. 10 This was conceived to conduce to the state and amplitude of their Empire. 1660R. Coke Power & Subj. 180 To the greater amplitude and glory of God. 1834Foster Pop. Ignor. 456 Religion, believed and felt, is the amplitude of our moral and intellectual nature.
5. Astr. The space by which a celestial body rises wide of due east, or sets wide of due west; its angular distance at rising or setting from the eastern or western point of the horizon.
When reckoned from the eastern and western points as shown by the compass, the Amplitude is Magnetic.
1627Smith Seaman's Gram. xv. 83 To obserue the..Amplitude. 1658Phillips s.v., The Amplitude of the Sun and Stars is an Arch of the Horizon, comprehended between the true East and West Point of it, and the Center of the Sun, Moon, or any Star, at its Rising or Setting. 1697W. Dampier Voy. (1729) I. 531 Taking the Suns Amplitude mornings and evenings. 1779Forrest Voy. N. Guinea 107 To day found the variation of the compass, by the medium of several amplitudes taken ashore. 1834Nat. Philos. III. xiii. 256/2 (U.K.S.) Amplitude..differs from the azimuth merely in being counted from the east and west points, instead of from north and south.
6. Extent of motion in space.
1880Darwin Movem. Plants 3 The great sweeps made by the stems of twining plants..result from a mere increase in the amplitude of the ordinary movement of circumnutation.
a. Hence in Gunnery, The range of a projectile.
1727–51Chambers Cycl., Amplitude of the range of a projectile denotes the horizontal line subtending the path in which it moved.
b. esp. in Physics. amplitude of a vibration: the distance which an individual particle moves from side to side in performing a complete vibration.
1837Brewster Magnetism 222 The diurnal oscillations have a small amplitude between the tropics. 1869Tyndall Light §220 The intensity of the light depends on the distance to which the ether particles move to and fro. This distance is called the amplitude of the vibration. The intensity of light is proportional to the square of the amplitude. 1876Blaserna Sound iii. 48 The loudness of a sound is represented by the amplitude of the vibrations causing it.
c. Electr. The maximum departure of the value of an alternating current or wave from the average value. Also attrib., as amplitude distortion.
1895S. P. Thompson Elementary Less. Electr. & Magn. x. 487 The impressed electromotive-force follows a sine law..where D is the maximum value or amplitude attained by E. 1931B.B.C. Year-Bk. 436/1 Amplitude Distortion, in electrical apparatus, the variation in response at different amplitudes with an input of constant frequency. 1945Electronic Engin. XVII. 640 Either the amplitude or the frequency of the sweep may be increased. 1953Amos & Birkinshaw Television Engin. I. i. 28 All the components of the vision signal must be reproduced at the correct amplitude to avoid distortion in the reproduced image.
d. Electr. amplitude modulation, modulation of a wave by variation of its amplitude; also, the system using such modulation (abbrev. A.M.). Cf. frequency modulation.
1921[see modulation 7]. 1922[see frequency modulation]. 1932F. E. Terman Radio Engin. x. 357 In all the commonly used systems of radio communication the intelligence is transmitted by varying the amplitude of the radiated waves... Communication carried on in this way is said to take place by means of amplitude modulation. 1942Electronic Engin. XIV. 630 The action of the limiter largely prevents the frequency distortion effect present with amplitude modulation. 1944Ibid. XVII. 58 An A.M. transmitter. 1962A. Nisbett Technique Sound Studio 240 Amplitude modulation (AM), a method whereby the information in an audio signal is carried on the much higher frequency of a radio wave. The envelope of the amplitude of the radio wave in successive cycles is equivalent to the wave form of the initial sound. Historically, AM is the method which was used first and such transmissions now crowd the short, medium and long wave bands... For high quality transmission AM has largely given way to FM (frequency modulation).
Add:[6.] [d.] Hence (as back-formations) amplitude-modulate v. trans.; amplitude-modulated ppl. a.
1938G. E. Sterling Radio Manual (ed. 3) vi. 353 An analysis of a frequency modulated wave shows that it contains the same side bands that are present in an amplitude modulated wave. 1970J. Earl Tuners & Amplifiers v. 104 The clicks, pops and whistles we commonly have to tolerate on a.m. stations are caused by the received signal being effectively amplitude-modulated by interference. 1982Giant Bk. Electronics Projects x. 463 This video output may in turn be used to amplitude modulate an rf carrier. 1990Physiotherapy LXXVI. 745/2 Both the medium frequency currents themselves, and the amplitude modulated beat frequency, are portrayed as sinusoidal. |