ray

1. A beam of light, heat, or other form of radiation. The rays from radium and other radioactive substances are produced by a spontaneous disintegration of the atom; they are electrically charged particles or electromagnetic waves of extremely short wavelength. 2. A part or branch that extends radially from a structure. [L. radius]
- actinic r. a light r. toward and beyond the violet end of the spectrum that acts upon a photographic plate and produces other chemical effects. SYN: chemical r..
- alpha r. SYN: alpha particle.
- anode rays those originating in a gas discharge tube and moving in a direction opposite to that of cathode rays; made up of positively charged ions. SYN: positive rays.
- Becquerel rays obsolete term for radiation given off by uranium and other radioactive substances; these include α, β, and γ rays.
- beta r. SYN: beta particle.
- cathode rays a stream of electrons emitted from the negative electrode (cathode) in a Crookes tube; their bombardment of the anode or the glass wall of the tube gives rise to x-rays.
- chemical r. SYN: actinic r..
- cosmic rays high-velocity particles of enormous energies, bombarding earth from outer space; the “primary radiation” consists of protons and more complex atomic nuclei that, on striking the atmosphere, give rise to neutrons, mesons, and other less energetic “secondary radiation.”
- direct rays SYN: primary rays (2).
- gamma rays electromagnetic radiation emitted from radioactive substances; they are high-energy x-rays but originate from the nucleus rather than the orbital shell and are not deflected by a magnet.
- glass rays those formed by cathode rays striking the wall of an x-r. tube; a special case of indirect rays and soft x-rays. Obsolete.
- grenz r. (grents) very soft x-rays, closely allied to the ultraviolet rays in their wavelength ( i.e., relatively long) and in their biologic action upon tissues; they are produced by a specially built vacuum tube with a hot cathode operating from a transformer delivering not more than 8 kw. [Ger. Grenze, borderline, boundary]
- H rays a stream of hydrogen nuclei; i.e., protons.
- hard rays rays of short wavelength and great penetrability.
- incident r. the r. that strikes the surface before reflection.
- indirect rays x-rays generated at a surface other than the anode target.
- intermediate rays those between ultraviolet and x-rays. SYN: W rays.
- marginal rays in geometric optics, those rays originating from the periphery.
- medullary r. the center of the renal lobule, which has the shape of a small, steep pyramid, consisting of straight tubular parts; these may be either ascending or descending limbs of the nephronic loop or collecting tubules. SYN: Ferrein pyramid, pars radiata lobuli corticalis renis, processus ferreini.
- Niewenglowski rays radiation emitted from a phosphorescent body after exposure to sunlight.
- parallel rays rays parallel to the axis of an optical system.
- paraxial rays in geometric optics, those rays focused at the principal point.
- positive rays SYN: anode rays.
- primary rays 1. cosmic rays in the form in which they first strike the atmosphere; 2. x-rays generated at the focal spot of the tube. SYN: direct rays.
- reflected r. a r. of light or other form of radiant energy which is thrown back from a nonpermeable or nonabsorbing surface; the r. which strikes the surface before reflection is the incident r..
- roentgen r. SYN: x-r. (1).
- secondary rays x-rays generated when primary x-r.'s impinge upon matter; scattered radiation.
- soft rays x-rays of relatively long wavelength and slight penetrability.
- supersonic rays rays with a wavelength higher than that perceptible to the human ear, above 20,000 Hz.
- W rays SYN: intermediate rays.
- x-r. x-r..

* * *

ray 'rā n any of numerous elasmobranch fishes (order Hypotremata) having the body flattened dorsoventrally, the eyes on the upper surface, and a much-reduced caudal region having typically a slender process often with venomous spines
ray n
1) one of the lines of light that appear to radiate from a bright object
2) a beam of radiant energy (as light) of small cross section
3 a) a stream of material particles traveling in the same line (as in radioactive phenomena)
b) a single particle of such a stream
rayed 'rād adj

* * *

(ra) [L. radius spoke] 1. a line emanating from a center. 2. a distinct portion of electromagnetic radiation that proceeds in a specific direction. 3. any of various marine elasmobranch fishes with flattened bodies and narrow tails. See also stingray.

Medical dictionary. 2011.

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  • Ray — Ray, n. [OF. rai, F. rais, fr. L. radius a beam or ray, staff, rod, spoke of a wheel. Cf. {Radius}.] 1. One of a number of lines or parts diverging from a common point or center, like the radii of a circle; as, a star of six rays. [1913 Webster]… …   The Collaborative International Dictionary of English

  • RAY (M.) — Pionnier, avec Marcel Duchamp et Picabia, du mouvement le plus radical de l’art moderne qui, de Dada au surréalisme, traverse jusqu’à notre époque tout le champ des arts visuels, Man Ray a largement contribué, par son œuvre polymorphe: tableaux,… …   Encyclopédie Universelle

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  • Ray — Ray, Man Ray, Nicholas Ray, Satyajit * * * (as used in expressions) Bradbury, Ray (Douglas) Charles, Ray Ray Charles Robinson Delany, Samuel R(ay) Eames, Charles y Ray Leonard, Sugar Ray Ray Charles Leonard Milland, Ray …   Enciclopedia Universal

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  • Ray — Saltar a navegación, búsqueda Ray puede referirse a: Abreviatura científica para el botánico John Ray (1627 1705) Ray Charles, cantante, pianista y artista Ray Bradbury, escritor estadounidense Ray Thompson, creador de la serie de culto La Tribu… …   Wikipedia Español

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