+A **cathode ray** is a stream of [electrons](/wiki/electron) observed in vacuum tubes. Emitted from a heated cathode, these rays travel in straight lines, causing luminescence when striking a phosphorescent surface, forming the basis of early [CRT](/wiki/crt) displays.
+## See also
+- [Electron](/wiki/electron)
+- [CRT](/wiki/crt)
+- [Vacuum Tube](/wiki/vacuum_tube)
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