cathode ray



  • A stream of electrons emitted by the cathode of a gas-discharge or vacuum tube, by a region immediately surrounding a cathode, or that emitted by a heated filament in certain electron tubes. Among other things, and depending on the circumstances, cathode rays directed onto a solid material may produce X-rays, phosphorescence, or heat. A CRT, for instance, can use focused electron beams directed onto a phosphor screen to produce images displayed by a TV. Please note that the term for a stream of electrons emitted from a radioactive chemical element is beta rays, not cathode rays.