Answer:
The primary components of a cathode ray tube (CRT) consist of a vacuum tube containing an electron gun and a screen lined with phosphors. CRTs are used to produce images.
The phosphors in a CRT’s screen are the materials that directly produce the photons generated by the CRT. These phosphors are struck by incoming electrons from the electron gun, absorb energy, and then re-emit some or all of that energy in the form of light.
CRT technology used to be common in televisions and computer monitors. Color CRTs contain three electron guns corresponding to three types of phosphors, one for each primary color (red, blue, and green). Examples of monochromatic CRTs include black and white TVs and old computer terminals.
Oscilloscopes, devices used to measure and display voltages, also use CRT displays. In this case, the persistence of the phosphor is more important than the color.
The CRTs in televisions and computer monitors bend the electron beams with magnetic deflection, while oscilloscopes rely on electrostatic deflection.
Key Terms
phosphor: A substance that exhibits the phenomenon of luminescence; often transition metal compounds or rare earth compounds of various types. The most common uses of phosphors are in CRT displays and fluorescent lights.
raster: A scanning pattern of parallel lines that form the display of an image projected on a cathode-ray tube of a television set or display screen.
electron gun: Any device that produces a stream of electrons, especially a narrow stream that is focused onto a phosphor screen.
