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 Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) |