optical negative
71Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… …
72motion picture, history of the — Introduction history of the medium from the 19th century to the present. Early years, 1830–1910 Origins The illusion of motion pictures is based on the optical phenomena known as persistence of vision and the phi phenomenon. The first …
73electromagnetic radiation — Physics. radiation consisting of electromagnetic waves, including radio waves, infrared, visible light, ultraviolet, x rays, and gamma rays. [1950 55] * * * Energy propagated through free space or through a material medium in the form of… …
74spectroscopy — spectroscopist /spek tros keuh pist/, n. /spek tros keuh pee, spek treuh skoh pee/, n. the science that deals with the use of the spectroscope and with spectrum analysis. [1865 70; SPECTRO + SCOPY] * * * Branch of analysis devoted to identifying… …
75Lightning — This article is about the atmospheric electrical phenomenon. For other uses, see Lightning (disambiguation). See also: Lightning strike Lightning striking Atlanta, United States Lightning is an atmospheric electrostatic discharge (spar …
76Microform — For other uses, see Microform (disambiguation). Digital scanning of microfilm (see Digital conversion below). Microforms are any forms, either films or paper, containing microreproductions[1] of documents for transmission, storage, reading, and… …
77Focal length — The focal length of an optical system is a measure of how strongly it converges (focuses) or diverges (diffuses) light. A system with a shorter focal length has greater optical power than one with a long focal length. Thin lens approximation For… …
78Diode — Figure 1: Closeup of a diode, showing the square shaped semiconductor crystal (black object on left) …
79Luminiferous aether — The luminiferous aether: it was hypothesised that the Earth moves through a medium of aether that carries light In the late 19th century, luminiferous aether or ether, meaning light bearing aether, was the term used to describe a medium for the… …
80Corrective lens — A bifocal corrective eyeglass lens A pair of contact le …
