cathode-ray tube

Vacuum tube in which a beam of electrons is produced and focused onto a fluorescent screen. The electrons' kinetic energy is converted into light energy as they collide with the screen. It is an essential component of one type of television receiver, of computer visual display units, and of oscilloscopes.

The screen of the CRT is coated on the inside with phosphor, which emits light when struck by an electron beam. The tube itself is glass and coated inside with a black graphite conducting paint, which is connected to one of three anodes. A heated filament heats a metal-oxide coated cathode that emits electrons which pass through a positively charged anode that is held at several thousand volts and accelerates the electrons to a high speed beam. The electrons accumulate on the phosphor of the screen and then flow into the conducting graphite paint, completing a circuit.