DICT.TW Dictionary Taiwan

 roentgen ray 名詞
 X射線,倫琴射線

 Ray, n.
 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.
 2. Bot. A radiating part of a flower or plant; the marginal florets of a compound flower, as an aster or a sunflower; one of the pedicels of an umbel or other circular flower cluster; radius. See Radius.
 3. Zool. (a) One of the radiating spines, or cartilages, supporting the fins of fishes. (b) One of the spheromeres of a radiate, especially one of the arms of a starfish or an ophiuran.
 4. Physics (a) A line of light or heat proceeding from a radiant or reflecting point; a single element of light or heat propagated continuously; as, a solar ray; a polarized ray. (b) One of the component elements of the total radiation from a body; any definite or limited portion of the spectrum; as, the red ray; the violet ray. See Illust. under Light.
 5. Sight; perception; vision; -- from an old theory of vision, that sight was something which proceeded from the eye to the object seen.
 All eyes direct their rays
 On him, and crowds turn coxcombs as they gaze.   --Pope.
 6. Geom. One of a system of diverging lines passing through a point, and regarded as extending indefinitely in both directions. See Half-ray.
 Bundle of rays. Geom. See Pencil of rays, below.
 Extraordinary ray Opt., that one of two parts of a ray divided by double refraction which does not follow the ordinary law of refraction.
 Ordinary ray Opt. that one of the two parts of a ray divided by double refraction which follows the usual or ordinary law of refraction.
 Pencil of rays Geom., a definite system of rays.
 Ray flower, or Ray floret Bot., one of the marginal flowers of the capitulum in such composite plants as the aster, goldenrod, daisy, and sunflower.  They have an elongated, strap-shaped corolla, while the corollas of the disk flowers are tubular and five-lobed.
 Ray point Geom., the common point of a pencil of rays.
 Roentgen ray, Röntgen ray Phys., a form of electromagnetic radiation generated in a very highly exhausted vacuum tube by an electrical discharge; now more commonly called X-ray.  It is composed of electromagnetic radiation of wavelength shorter than that of ultraviolet light but longer than that of gamma rays.  It is capable of passing through many bodies opaque to light, and producing photographic and fluorescent effects by which means pictures showing the internal structure of opaque objects are made, called X-rays, radiographs, sciagraphs, X-ray photographs, radiograms. So called from the discoverer, W. C. Röntgen.
 X ray, the Röntgen ray; -- so called by its discoverer because of its enigmatical character, x being an algebraic symbol for an unknown quantity.

 Röntgen ray, Roentgen ray.  Physics An X-ray; originally, the term was applied to any of the rays produced when cathode rays strike upon surface of a solid (as the wall of the vacuum tube), but now it refers specifically to electromagnetic radiation having wavelengths from 10-3 nm to 10 nm, immediately below ultraviolet radiation on the wavelength scale.  Röntgen rays are noted for their penetration of opaque substances, as wood and flesh, their action on photographic plates, and their fluorescent effects.  They were called X rays by their discoverer, W. K. Röntgen.  They are one of the forms of ionizing radiation, which can have damaging effects on living cells.  They also ionize gases, but cannot be reflected, or polarized, or deflected by a magnetic field.  They are used in examining opaque objects, especially in medicine for visualizing organs and other objects inside the human body, as for locating fractures or bullets, and examining internal organs for abnormalities.
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 roentgen ray
      n : electromagnetic radiation of short wavelength produced when
          high-speed electrons strike a solid target [syn: X ray,
           X-radiation]