Columbia Encyclopedia

Search results

500 results found

reggae

(Encyclopedia)reggae, Jamaican popular music that developed in the 1960s among Kingston's poor blacks, drawing on American “soul” music and traditional African and Jamaican folk music and ska (a Jamaican and Br...

electromagnet

(Encyclopedia)CE5 Electromagnet electromagnet, device in which magnetism is produced by an electric current. Any electric current produces a magnetic field, but the field near an ordinary straight conductor is ...

pacemaker, artificial

(Encyclopedia)pacemaker, artificial, device used to stimulate a rhythmic heartbeat by means of electrical impulses. Implanted in the body when the heart's own electrical conduction system (natural pacemaker) does n...

welding

(Encyclopedia)welding, process for joining separate pieces of metal in a continuous metallic bond. Cold-pressure welding is accomplished by the application of high pressure at room temperature; forge welding (forgi...

Moissan, Henri Ferdinand Frederick

(Encyclopedia)Moissan, Henri Ferdinand Frederick, 1852–1907, French chemist, Ph.D. École Pratique des Haute Études, Paris, 1880. Moissan was a professor at the School of Pharmacy in Paris (1886–1900) and at t...

Siemens, Ernst Werner von

(Encyclopedia)Siemens, Ernst Werner von ĕrnst vĕrˈnər fən zēˈməns [key], 1816–92, German electrical engineer and inventor. He was a founder and director of Siemens and Halske, a firm that made electrical ...

volt

(Encyclopedia)volt [for Alessandro Volta], abbr. V, unit of electric potential and electromotive force. It is defined as the difference of electric potential existing across the ends of a conductor carrying a const...

Wheatstone, Sir Charles

(Encyclopedia)Wheatstone, Sir Charles hwētˈstōn, –stən [key], 1802–75, English physicist and inventor. He was professor at King's College, London, from 1834. A pioneer in telegraphy, he was coinventor with ...

logic circuit

(Encyclopedia)logic circuit, electric circuit whose output depends upon the input in a way that can be expressed as a function in symbolic logic; it has one or more binary inputs (capable of assuming either of two ...

power, in physics

(Encyclopedia)power, in physics, time rate of doing work or of producing or expending energy. The unit of power based on the English units of measurement is the horsepower, devised for describing mechanical power b...