A plate, usually called anode in Britain, is a type of electrode that forms part of a vacuum tube.[1] It is usually made of sheet metal, connected to a wire which passes through the glass envelope of the tube to a terminal in the base of the tube, where it is connected to the external circuit. The plate is given a positive potential, and its function is to attract and capture the electrons emitted by the cathode. Although it is sometimes a flat plate, it is more often in the shape of a cylinder or flat open-ended box surrounding the other electrodes.
- ^ Thomas A. Edison U.S. patent 307,031 "Electrical Indicator", Issue date: 1884