thermionic emission. Starting in 1901, Owen Richardson studied this phenomenon and in 1929 he received the Nobel prize in Physics for his work. A hot wire will be surrounded by evaporated electrons. An electric force can pull these electrons away from the wire — the larger the electric force, the larger the resulting current of electrons.
In thermionic emission, the heat supplies some electrons with at least the minimal energy required to overcome the attractive force holding them in the structure of the metal. This minimal energy, called the work function, is characteristic of the emitting material and the state of contamination of its surface. See also field emission.
7/14/2018 · Thermionic emission is the discharge of electrons from heated materials , widely used as a source of electrons in conventional electron tubes ( e.g.
television picture tubes) in the fields of electronics and communications . The phenomenon was first observed (1883) by Thomas A. Edison as a passage of electricity from a filament to a plate of metal …
The emission of free electrons from a ‘hot’ metal surface is called Thermionic E mission If we put a negative plate in front of our hot metal any electrons that are emitted will be pushed back towards the metal by the negative charge on the plate. None of them will get very far from the metal.
5/1/2020 · Modern vacuum tubes use thermionic emission, in which the cathode is made of a thin wire filament which is heated by a separate electric current passing through it. The increased random heat motion of the filament atoms knocks electrons out of the atoms at the surface of the filament, into the evacuated space of the tube.
Owen Willans Richardson, John Ambrose Fleming, Edmond Becquerel, Walter H. Schottky, Saul Dushman, Vacuum Tube, Hot Cathode, Electron Gun, Field Emission Gun, Photoelectric Effect
