| radiant energy | Energy contained in light rays or any other form of radiation. (05 Mar 2000) |
|---|---|
| mass energy absorption coefficient | <physics> The mass energy absorption coefficient, uen/p of a material for uncharged ionising particles is the product of the mass energy transfer coefficient, utr/p and (1 - g) where g is the fraction of the energy of secondary charged particles that is lost to bremsstrahlung in the material. (16 Dec 1997) |
| radiant | 1. Emitting or proceeding as from a center; rays; radiating; radiate. 2. Especially, emitting or darting rays of light or heat; issuing in beams or rays; beaming with brightness; emitting a vivid light or splendor; as, the radiant sun. "Mark what radiant state she spreads." (Milton) 3. Beaming with vivacity and happiness; as, a radiant face. 4. Giving off rays; said of a bearing; as, the sun radiant; a crown radiant. 5. <botany> Having a raylike appearance, as the large marginal flowers of certain umbelliferous plants; said also of the cluster which has such marginal flowers. <physics> Radiant energy See Radiant. Origin: L. Radians, -antis, p. Pr. Of radiare to emit rays or beams, fr. Radius ray: cf. F. Radiant. See Radius, Ray a divergent line. 1. <optics> The luminous point or object from which light emanates; also, a body radiating light brightly. 2. <geometry> A straight line proceeding from a given point, or fixed pole, about which it is conceived to revolve. 3. <astronomy> The point in the heavens at which the apparent paths of shooting stars meet, when traced backward, or whence they appear to radiate. Source: Websters Dictionary (01 Mar 1998) |
| radiant heat | Heat given off from any body in the form of waves, similar to light waves but of greater wavelength. (05 Mar 2000) |
| radiant intensity | The luminous flux per unit solid angle in a given direction. Synonym: candle-power, radiant intensity. (05 Mar 2000) |
| absorption | The process of absorbing, specifically: 1. <physiology> The movement and uptake of substances (liquids and solutes) into cells or across tissues such as skin, intestine and kiidney tubules, by way of diffusion or osmosis. 2. <chemistry> The drawing of a gas or liquid into the pores of a permeable solid. 3. <psychology> The devotion of thought to one object or activity, with inattention to others. 4. <radiology> The taking up of energy by matter with which the radiation interacts. 5. <physics> The loss of (electromagnetic) energy to a medium. For instance, an electromagnetic wave which propagates through a plasma will set the electrons into motion. If the electrons make collisions with other particles, they will absorb net energy from the wave. 6. <immunology> A process in which an antigen or antibody is used to pull an analogous antigen or antibody out of a solution. Compare: adsorption. Origin: L. Absorptio (12 Nov 1997) |
| absorption band | The range of wavelengths or frequencies in the electromagnetic spectrum where radiant energy is absorbed by passage through a gaseous, liquid, or dissolved substance; it is exploited for analytical purposes in colourimetry or spectrophotometry, and is usually described in terms of the wavelength where maximum absorbance occurs (i.e., lambdamax). (05 Mar 2000) |
| absorption cell | A small glass chamber with parallel sides, in which absorption spectra of solutions can be obtained. (05 Mar 2000) |
| absorption chromatography | <investigation> Techniques for separating molecules based on differential absorption and elution. Term for separation methods involving flow of a fluid carrier over a nonmobile absorbing phase. (18 Nov 1997) |
| absorption coefficient | <physics> Measures the degree of wave absorption defined as the fraction of wave energy lost as the wave travels a unit distance. See: absorption. (15 Jan 1998) |
| absorption collapse | Pulmonary collapse due to rapid complete obstruction of a large bronchus. (05 Mar 2000) |
| absorption fever | An elevation of temperature often occurring, without other untoward symptoms, shortly after childbirth, assumed to be due to absorption of uterine discharges through abrasions of the vaginal wall. (05 Mar 2000) |
| absorption lines | The dark line's in the solar spectrum due to absorption by the solar and the earth's atmosphere; the phenomenon occurs because rays passing from an incandescent body through a colder medium are absorbed by elements in that medium. (05 Mar 2000) |
| absorption spectroscopy | <investigation> This is the use of a spectrophotometer to measure the ability of particles (solutes) in a solution to absorb light through a range of specific wavelengths. Every compound absorbs light differently, so absorption spectra can be used to identify compounds, measure concentrations, and determine reaction rates. (15 Jan 1998) |
| absorption spectrum | <chemistry> A graph of the amount of light a substance absorbs, plotted as a fuction of energy, frequency or wavelength. (15 Jan 1998) |