Why do TV screens emit light

Luminescence is the emission of light by certain materials when they are relatively cool, in contrast to light emitted during incandescence, such as when a candle bums, 

The name luminescence is generally accepted for all the light-emission phenomena not caused solely by a rise in temperature (as above), but in fact incorporates the different categories of phosphorescence and fluorescence, although the distinctions between the terms is still in some dispute. 

A colour TV screen operates in the same way as a black and white machine, except that the inside of the screen is coated with thousands of groups of dots each group consists of three dots, one each for red, green and blue. 

The kinetic energy of the electron from the electron gun is absorbed by the phosphor, and re-emitted as the visible light seen by the viewer. 

The groups of dots are called picture elements - or pixels for short. 

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