The Electron: Thermionic Emission

Thermionic emission: The emission of electrons from the surface of a hot metal Temperature requirement: >800 degrees Celsius

Work function: The minimum energy needed to remove an electron from a metal to a point in the vacuum immediately outside the solid surface

Cathode Ray Tube

A low voltage is placed across the filament, making current flow This causes the cathode to heat up and thermionic emission to occur Electrons accelerate towards the anode and to the end of the tube in a vacuum This beam of electrons is a straight line The screen at the end of the tube is fluoresecent (coated with phosphor) and when electrons hit this screen their kinetic energy is converted into light

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