A television is an electronic device which produces audio and visual effect simultaneously. It is not only a means of entertainment but also a great source of education. The basic theory of television was developed by the English scientists, Ayrton and Perry in 1806. The idea developed by them was called Electric vision.
Televisions are of two types: black and white, and colour. Colour television functions quite like a black and white television set but its working is much more complex.
The colour television has mirrors inside the camera which divide the light into three parts. There are three filters inside the camera, one for each part of the light. One filter allows only red light to pass, another allows only green and the third only blue. Each colour goes to a different camera tube and each tube has a separate glass plate and electron beam. From the three tubes three signals go to the transmitter.
The colour television transmitter multiplexes three signals into one. To this resultant signal a black and white signal is added. This combined signal is sent to the broadcasting antenna. From here this signal reaches our television.
In colour sets three electron beams – red, green and blue, scan the screen which when mixed together give full colour picture. The screen of the picture tube is coated with 
million tiny dots of phospher, each arranged into a group of three. A phospher is a substance that emits light when an electron beam falls on it. Each of the three phosphers emits three colours – red, blue and green. So the blue phospher emits blue light when the electron beam carrying the blue light signal falls on it, and so on. The colour produced at each group of dots depends on the intensity of the electron beams. To make sure that each beam produces the right colour, the beams pass through holes in a shadow mask behind the screen. These three colours can be produced in different proportions to give all the other colours of the original.
In a modern television set, all its functions can be regulated by remote control system which includes sound adjustments, colour perfection, channel changing and so on.
