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Television
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On a TV set pictures and sounds are broadcast by electric cable or radio
waves. A TV set consists of a cathode-ray tube which makes 525 lines (in
the USA) on screen by an electron beam. All this creates a complete picture
on the screen and 30 pictures per second are used to see a flicker-free
film. The lights of the television camera are filtered into three primary
colours (red, green and blue) and these are sent to the television recievers.
These primary signals are demodulated and the reciever applies the three
colour components to three separate electron guns which create the coloured
picture on the screen. Color television was introduced in the USA in 1951.
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