Learn about TVs in this educational video from dizzo95.
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Female Speaker: A TV image is made of hundreds of lines that are in turn made of hundreds of dots. When a color television receives a video, it decodes the signal into three separate signals, one for each of the primary colors; red, green and blue. The colors you see on your TV are created by adding various levels of these three colors. In fact the TV tube are three electron guns, one for each color, that emit beams which scan the screen in a series of lines. In each line are rows of dots. The dots are in groups of three; red, green and blue, which are made of color phosphorous that glow when struck by the electron beams. If the beam scans line by line across the tube, triggering the tiny dots, a color image is reconstructed, to make sure that the beams from the electron gun hit the right color dot. A black shadow mask with holes for each dot is placed between the dots and the gun. In American TVs, the beams scan 525 lines, 30 times a second. The combination of the speed of the scan and the lag effect the glowing phosphorous create the illusion of a continuos image on the screen.

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