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DictionarySeelawreciprocity law
reciprocity law[‚res·ə′präs·əd·ē ‚lȯ] (graphic arts) The law that, with standard development, the optical density of an exposed emulsion is proportional to the exposure time and to the illumination. reciprocity law
Bun·sen-Ros·coe law (bŭn'sĕn ros'kō), in two photochemical reactions, for example, the darkening of a photographic plate or film, if the products of the intensity of illumination and the time of exposure are equal, the quantities of chemical material undergoing change will also be equal; the retina for short periods of exposure obeys this law. Synonym(s): reciprocity law, Roscoe-Bunsen lawreciprocity lawAny milliamperage multiplied by an exposure time setting that gives the same milliamperage-second outcome should give the same relative density to an image. However, this law is dramatically affected by the image receptor response curve, esp. when it is not a 45° linear curve. In radiographic intensifying film and screen technologies, the reciprocity law does not hold at long exposure times because of the reversal of the D log E response curve. See also: lawBunsen, Robert W., German chemist and physicist, 1811-1899. Bunsen burner - a gas lamp giving a very hot but only slightly luminous flame.Bunsen solubility coefficient - the milliliters of gas STPD dissolved per milliliter of liquid and per atmosphere (760 mmHg) partial pressure of the gas at any given temperature.Bunsen-Roscoe law - in two photochemical reactions, if the product of the intensity of illumination and the time of exposure are equal, the quantities of chemical material undergoing change will be equal. Synonym(s): reciprocity law; Roscoe-Bunsen lawRoscoe-Bunsen law - Synonym(s): Bunsen-Roscoe law |