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fireball

(Encyclopedia)fireball, very bright meteor leaving a trail in the sky that can remain visible for several minutes; often a distinct sound, perhaps caused by very low frequency radio waves, is associated with it. A ...

Arsonval, Arsène d'

(Encyclopedia)Arsonval, Arsène d' ärsĕnˈ därsôNvälˈ [key], 1851–1940, French physicist and physician. He worked under Claude Bernard and under C. E. Brown-Séquard (whom he succeeded in 1897 at the Collè...

crossing over

(Encyclopedia)crossing over, process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis. At that stage each ...

Caslon, William

(Encyclopedia)Caslon, William kăzˈlən [key], 1692–1766, English type designer, b. Worcestershire. He worked first in London as an engraver of gunlocks, then set up his own foundry in 1716. The merits of Caslon...

sleep

(Encyclopedia)sleep, resting state in which an individual becomes relatively quiescent and relatively unaware of the environment. During sleep, which is in part a period of rest and relaxation, most physiological f...

Munk, Walter Heinrich

(Encyclopedia)Munk, Walter Heinrich, 1917–2019, American oceanographer and geophysicist, b. Vienna (then in Austria-Hungary), B.S. California Institute of Technology, 1939, Ph.D Univ. of California, Los Angeles, ...

commutator

(Encyclopedia)commutator, device used in an electric generator to convert the alternating current produced in the generator into direct current before the current is sent into an external circuit; it is basically a...

static

(Encyclopedia)static, term formerly use to describe electrical noise in radio reception, especially noise that originates outside a transmitter and receiver, e.g., in the atmosphere or in human-made devices. In gen...

impedance

(Encyclopedia)impedance, in electricity, measure in ohms of the degree to which an electric circuit resists the flow of electric current when a voltage is impressed across its terminals. Impedance is expressed as t...

Zeeman effect

(Encyclopedia)Zeeman effect, splitting of a single spectral line (see spectrum) into a group of closely spaced lines when the substance producing the single line is subjected to a uniform magnetic field. The effect...