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Voltage spawning a cathode ray

  1. Jun 16, 2012 #1
    In descriptions of the cathode ray, various sites mention how the ray is formed from a voltage applied to the tube which spawns the ray on sees in the vacuum tube. Could someone elaborate on how a voltage can spawn this beam? As in, where does the potential difference come from and so on.

    Thank you
  2. jcsd
  3. Jun 16, 2012 #2


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    A "cathode ray" is simply an electron that has been emitted from the cathode and accelerated by the negative voltage applied. (Or a positive voltage from an anode) The electrons can be emitted through "thermionic emission" by heating the cathode, or a "cold cathode" can be used in which a very high voltage ionizes the remaining gas inside an evacuated vacuum tube.

  4. Jun 18, 2012 #3
    Thank you! :smile:
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