Columbia Encyclopedia

Search results

500 results found

Ohm's law

(Encyclopedia)Ohm's law ōm [key] [for G. S. Ohm], law stating that the electric current i flowing through a given resistance r is equal to the applied voltage v divided by the resistance, or i=v/r. For general app...

inductor

(Encyclopedia)inductor, electric device consisting of one or more turns of wire and typically having two terminals. An inductor is usually connected into a circuit in order to raise the inductance to a desired valu...

Wood, Robert Williams

(Encyclopedia)Wood, Robert Williams, 1868–1955, American physicist, b. Concord, Mass., grad. Harvard (B.A., 1891). After studying abroad he became associated with Johns Hopkins as professor of experimental physic...

waveguide

(Encyclopedia)waveguide, device that controls the propagation of an electromagnetic wave so that the wave is forced to follow a path defined by the physical structure of the guide. Waveguides, which are useful chie...

Birkeland, Kristian

(Encyclopedia)Birkeland, Kristian or Olaf Christian krĭsˈtyän bērˈkəlän, ōˈläv [key], 1867–1917, Norwegian physicist. From 1898 Birkeland was a professor at the Univ. of Christiania (now Oslo). Noted fo...

macular degeneration

(Encyclopedia)macular degeneration, eye disorder causing loss of central vision. The affected area, the macula, lies at the back of the retina and is the part that produces the sharpest vision. The most serious vis...

Esztergom

(Encyclopedia)Esztergom ĕˈstĕrgôm [key], Ger. Gran, city (1991 est. pop. 29,751), N Hungary, on the Danube River and the border of Slovakia. It is a county administrative center, a river port, and a railroad te...

Kassel

(Encyclopedia)Kassel käsˈəl [key], city (1994 pop. 202,160), Hesse, central Germany, on the Fulda River. It is an industrial, rail, and cultural center. Manufactures include textiles, optical and precision instr...

Bettelheim, Bruno

(Encyclopedia)Bettelheim, Bruno bĕtˈəlhīmˌ [key], 1903–90, American developmental psychologist, b. Austria. He received his doctoral degree (1938) from the Univ. of Vienna. He was imprisoned in the Dachau an...

nervous system

(Encyclopedia)CE5 Nerve cell CE5 Nervous system nervous system, network of specialized tissue that controls actions and reactions of the body and its adjustment to the environment. Virtually all members of ...