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electrostatics
electrostatics study of phenomena associated with charged bodies at rest (see charge ; electricity ). A charged body has an excess of positive or negative charges, a condition usually brought about by the transfer of electrons to or from the body. Such bodies exert forces on each other, as descri...
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Chester Floyd Carlson
Chester Floyd Carlson 1906-68, American inventor; b. Seattle, Wash. A patent lawyer, he invented (1938) xerography , a method of electrostatic printing. For the next two decades he struggled to find a company that would produce his copying machine, finally finding the Haloid Co., which first marke...
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electric potential
electric potential work per unit of electric charge expended in moving a charged body from a reference point to any given point in an electric field (see electrostatics ). The potential at the reference point is considered to be zero, and the reference point itself is usually chosen to be at inf...
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cathode-ray tube
cathode-ray tube special-purpose electron tube in which electrons are accelerated by high-voltage anodes, formed into a beam by focusing electrodes, and projected toward a phosphorescent screen that forms one face of the tube. The beam of electrons leaves a bright spot wherever it strikes the phosp...
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Siméon Denis Poisson
Siméon Denis Poisson , 1781-1840, French mathematician and physicist. From 1802 he taught at the École polytechnique, Paris, and was also on the faculty of sciences at the Univ. of Paris from 1809. His chief interest lay in the application of mathematics to physics, especially in elect...
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capacitor
capacitor or condenser, device for the storage of electric charge. Simple capacitors consist of two plates made of an electrically conducting material (e.g., a metal) and separated by a nonconducting material or dielectric (e.g., glass, paraffin, mica, oil, paper, tantalum, or air). The Leyden...
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charge
charge property of matter that gives rise to all electrical phenomena (see electricity ). The basic unit of charge, usually denoted by e, is that on the proton or the electron ; that on the proton is designated as positive (+ e ) and that on the electron is designated as negative (- e ). All ...
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induction
induction in electricity and magnetism, common name for three distinct phenomena. Electromagnetic induction is the production of an electromotive force (emf) in a conductor as a result of a changing magnetic field about the conductor and is the most important of the three phenomena. It was di...
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loudspeaker
loudspeaker or speaker, device used to convert electrical energy into sound. It consists essentially of a thin flexible sheet called a diaphragm that is made to vibrate by an electric signal from an amplifier . The vibrations create sound waves in the air around the speaker. In a dynamic speak...
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microphone
microphone device for converting sound into electrical energy, used in radio broadcasting, recording, and sound amplifying systems. Its basic component is a diaphragm that responds to the pressure or particle velocity of sound waves. The microphone, various forms of which were developed independent...
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