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photon

(Encyclopedia)photon fōˈtŏn [key], the particle composing light and other forms of electromagnetic radiation, sometimes called light quantum. The photon has no charge and no mass. About the beginning of the 20th...

scintillation counter

(Encyclopedia)scintillation counter, device for detecting and measuring radiation by means of tiny visible flashes produced by the radiation when it strikes a sensitive substance known as a phosphor (see phosphores...

Millikan, Robert Andrews

(Encyclopedia)Millikan, Robert Andrews mĭlˈĭkən [key], 1868–1953, American physicist and educator, b. Morrison, Ill., grad. Oberlin College, 1891, Ph.D. Columbia, 1895, studied in Germany. He taught (1896–1...

Einstein, Albert

(Encyclopedia)Einstein, Albert īnˈstīn [key], 1879–1955, American theoretical physicist, known for the formulation of the relativity theory, b. Ulm, Germany. He is recognized as one of the greatest physicists ...

optical sensing

(Encyclopedia)optical sensing, in general, any method by which information that occurs as variations in the intensity, or some other property, of light is translated into an electric signal. This is usually accompl...

photocell

(Encyclopedia)photocell: see photoelectric cell. ...

photomultiplier

(Encyclopedia)photomultiplier: see photoelectric cell. ...

electric eye

(Encyclopedia)electric eye: see photoelectric cell. ...

photovoltaic cell

(Encyclopedia)photovoltaic cell: see photoelectric cell; solar cell. ...

GEM, acronym for ground-effect machine

(Encyclopedia)GEM: see air-cushion vehicle.