- cathode ray
a flow of electrons emanating from a cathode in a vacuum tube and focused into a narrow beam.[1875-80]
* * *Stream of electrons leaving the negative electrode, or cathode, in an evacuated or gas-filled discharge tube or emitted by a heated filament in certain electron tubes.Cathode rays cause fluorescent materials to luminesce and are utilized in cathode-ray oscilloscopes and television tubes (see cathode-ray tube).
* * *▪ physicsstream of electrons leaving the negative electrode (cathode) in a discharge tube containing a gas at low pressure, or electrons emitted by a heated filament in certain electron tubes. Cathode rays focused on a hard target (anticathode) produce X-rays or focused on a small object in a vacuum generate very high temperatures (cathode-ray furnace). When cathode rays strike certain molecules used to coat a cathode screen, they cause the molecules (and hence the screen) to emit light. This effect, when coupled with the controlled deflection of a cathode ray by electric or magnetic fields, gives rise to the cathode-ray oscilloscope (cathode-ray tube [CRT]) for monitoring variations and values of an alternating voltage or current and to the picture tube of television and radar.
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