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Trollhättan

(Encyclopedia)Trollhättan trôlˈhĕˌtän [key], city (1990 pop. 40,180), Älvsborg co., S Sweden, on the Götaälv River near Lake Vänern. The Götaälv River, which falls 108 ft (33 m) in about 1 mi (1.6 km) a...

Grünberg, Peter Andreas

(Encyclopedia)Grünberg, Peter Andreas pāˈtər ändrāˈäs grünbĕrkˈ [key], 1939–2018 German physicist, b. Pilsen, Germany (now Plzeň, Czech Republic). After receiving his Ph.D. at the Darmstadt Univ. of T...

electromotive force

(Encyclopedia)electromotive force, abbr. emf, difference in electric potential, or voltage, between the terminals of a source of electricity, e.g., a battery from which no current is being drawn. When current is dr...

scanning tunneling microscope

(Encyclopedia)scanning tunneling microscope (STM), device for studying and imaging individual atoms on the surfaces of materials. The instrument was invented in the early 1980s by Gerd Binnig and Heinrich Rohrer, w...

Debye, Peter Joseph Wilhelm

(Encyclopedia)Debye, Peter Joseph Wilhelm dēbīˈ [key], 1884–1966, American physicist, b. the Netherlands. He was professor at the universities of Zürich, Utrecht, Göttingen, Leipzig, and Berlin. In 1940 he c...

magnetic resonance

(Encyclopedia)magnetic resonance, in physics and chemistry, phenomenon produced by simultaneously applying a steady magnetic field and electromagnetic radiation (usually radio waves) to a sample of atoms and then a...

alternating current

(Encyclopedia)alternating current, abbr. AC, a flow of electric charge that undergoes periodic reverses in direction. In North America ordinary household current alternates at a frequency of 60 times per second. Se...

Ross, Sir James Clark

(Encyclopedia)Ross, Sir James Clark, 1800–1862, British polar explorer and rear admiral. In 1818 he accompanied his uncle, Sir John Ross, in search of the Northwest Passage and commanded the Erebus. He later stud...

Reventazón

(Encyclopedia)Reventazón rāvāntäsōnˈ [key], river, c.85 mi (140 km) long, rising in the Meseta Central, E Costa Rica, and flowing NE to the Caribbean Sea, N of Limón. The Reventazón is navigable for a short...

Rjukan

(Encyclopedia)Rjukan rēo͞oˈkän [key], town, Telemark co., S Norway, on the Rjukanfoss, one of several high waterfalls of the Måne River. Its large power stations supply electricity to saltpeter and chemical fe...