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sonar

(Encyclopedia)sonar sōˈnär [key], device used underwater for locating submerged objects and for submarine communication by means of sound waves. The term sonar is an acronym for sound navigation ranging. The mai...

diode

(Encyclopedia)diode dīˈōd [key], two-terminal electronic device that permits current flow predominantly in only one direction. Most diodes are semiconductor devices; diode electron tubes are now used only for a ...

Hufstedler, Shirley Mount

(Encyclopedia)Hufstedler, Shirley Mount, 1925–2016, American jurist and U.S. secretary of education (1980–81), b. Denver, as Shirley Ann Mount, grad. Univ. of New Mexico (B.B.A. 1945) and Stanford Law School (L...

Northfield

(Encyclopedia)Northfield, city (1990 pop. 14,684), Rice co., SE Minn., near Minneapolis–St. Paul, on the Cannon River; inc. 1875. It is the trade center for a dairy and farming region. Manufactures include printe...

Van Devanter, Willis

(Encyclopedia)Van Devanter, Willis văn dēvănˈtər [key], 1859–1941, American jurist, associate justice of the U.S. Supreme Court (1910–37), b. Marion, Ind. He practiced law (1881–84) in Indiana and, after...

Edison, Thomas Alva

(Encyclopedia)Edison, Thomas Alva, 1847–1931, American inventor, b. Milan, Ohio. A genius in the practical application of scientific principles, Edison was one of the greatest and most productive inventors of his...

turbine

(Encyclopedia)CE5 Types of turbines turbine, rotary engine that uses a continuous stream of fluid (gas or liquid) to turn a shaft that can drive machinery. A water, or hydraulic, turbine is used to drive electr...

magnetism

(Encyclopedia)CE5 Lines of induction around a single bar magnet and between opposite poles of different magnets magnetism, force of attraction or repulsion between various substances, especially those made of i...

Hertz, Heinrich Rudolf

(Encyclopedia)Hertz, Heinrich Rudolf hĕrts [key], 1857–94, German physicist. He confirmed J. C. Maxwell's electromagnetic theory and in the course of experiments (1886–89) produced and studied electromagnetic...

MacCready, Paul Beattie

(Encyclopedia)MacCready, Paul Beattie, 1925–2007, American engineer and inventor known for his achievements in human-powered flight, b. New Haven, Conn., Ph.D. California Institute of Technology, 1952. In 1997 he...