![]() ![]() The electric field accelerated the ions and the ions released electrons from the cathode when they collided with the cathode. The early cold cathode vacuum tubes, called Crookes tubes, used a high electrical potential between the anode and the cathode to ionize the residual gas in the tube. To release electrons into the tube, they must first be detached from the atoms of the cathode. The image in a classic television set is created by focused beam of electrons deflected by electric or magnetic fields in cathode ray tubes (CRTs).Ĭathode rays are so named because they are emitted by the negative electrode, or cathode, in a vacuum tube. Electrons were first discovered as the constituents of cathode rays. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, the glass opposite the negative electrode is observed to glow from electrons emitted from the cathode. crookes tube: An early experimental electrical discharge tube, invented by English physicist William Crookes and others around 1869-1875, in which cathode rays, streams of electrons, were discoveredĬathode rays (also called electron beams or an e-beams) are streams of electrons observed in vacuum tubes. ![]() cathode rays: Streams of electrons observed in vacuum tubes.Thomson used the cathode ray tube to determine that atoms had small negatively charged particles inside of them, which he called “electrons.” Cathode rays carry electronic currents through the tube. ![]()
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