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Kennelly, Arthur Edwin

(Encyclopedia)Kennelly, Arthur Edwin kĕnˈəlē [key], 1861–1939, American electrical engineer, b. Bombay (now Mumbai), India, educated at University College School, London. He was Edison's chief electrical assi...

microwave

(Encyclopedia)microwave, electromagnetic wave having a frequency range from 1,000 megahertz (MHz) to 300,000 MHz, corresponding to a wavelength range from 300 mm (about 12 in.) to 1 mm (about 0.04 in.). Like light ...

dark matter

(Encyclopedia)dark matter, material that is believed to make up nearly 27% of the mass of the universe but is not readily visible because it neither emits nor reflects electromagnetic radiation, such as light or ra...

thermosets

(Encyclopedia)thermosets, materials that can not be softened on heating. In thermosetting polymers, the polymer chains are joined (or cross-linked) by intermolecular bonding. Thermosets are usually supplied as part...

Ritz, Walter

(Encyclopedia)Ritz, Walter, 1878–1909, Swiss physicist. He taught at the universities of Zürich and Göttingen. Ritz's combination principle, confirmed by later research, stated that the frequencies of spectral ...

noise

(Encyclopedia)noise, any signal that does not convey useful information. Electrical noise consists of electrical currents or voltages that interfere with the operation of electronic systems. Electrical noise limits...

biophysics

(Encyclopedia)biophysics, application of various methods and principles of physical science to the study of biological problems. In physiological biophysics physical mechanisms have been used to explain such biolog...

beta particle

(Encyclopedia)beta particle, one of the three types of radiation resulting from natural radioactivity. Beta radiation (or beta rays) was identified and named by E. Rutherford, who found that it consists of high-spe...

elementary particles

(Encyclopedia)CE5 elementary particles, the most basic physical constituents of the universe. The first subatomic particle to be discovered was the electron, identified in 1897 by J. J. Thomson. After the...

color index

(Encyclopedia)color index, in astronomy, difference in an object's brightness as recorded between any two well-defined bands of the electromagnetic spectrum by using optical filters of different colors. If blue and...