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cathode rays
A stream of electrons emitted from the negatively-charge electrode, or cathode, when an electric discharge takes place in a vacuum tube, i.e. a tube containing a gas at very low pressure. The existence of cathode rays first became known to science in 1838 when the British experimenter Michael Faraday passed current through a vacuum tube and noticed an arc of light stretching almost from the cathode to the anode. This suggested that something was traveling in a straight line across the tube from the cathode – a "something" that became known as cathode rays. Scientists debated whether these rays consisted of waves, such as X-rays, or particles. Eventualy, J. J. Thomson, working at the Cavendish Laboratory, showed that cathode rays consisted of streams of tiny negatively-charged particles, which he identified as electrons.
Related categories
• ATOMIC AND NUCLEAR PHYSICS
• HISTORY OF SCIENCE
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