The radio communicates only sounds. The television can communicate both picture and sound. Sitting in one’s drawing room one can see what is happening throughout the world, if the events are telecast. During the Kargil war in 1999, one could see the war on the television as it was unfolding in Kashmir. Television was invented by T.L. Baird in 1926 and its use is widespread now throughout the world.
The working process of a television depends upon four actions. They are:
1. Scanning the object to be telecast.
2. Conversion of the light impulses received from the scanned object into light electric waves.
3. Conversion of the sound waves into electric waves. The above three are to be done by the television transmitter.
4. Reconstruction of the electrical waves into light impulses and sound weaves is to be done by the television receiver. In the radio, the sound waves are converted into electric waves by microphone. Here light impulses are also converted into electric waves. The conversion of light waves to electric waves is done by chronoscope now replaced by a device known as image orthicon. The light and sound waves thus converted into electric waves are transmitted by the television transmitter.
It was possible to get a food radio transmission by the method of sky way transmission as ionosphere was reflecting the sound waves back to earth. Here the light waves penetrate and pass out of the ionosphere. So some other object is required to do that work.
In television this transmission back to earth is done by geostationary satellites, stationed at an altitude of 36,000 kms. From the earth’s surface. The electrical waves thus directed are received by antenna, and the electrical waves are reconverted into sound and light impulses by T.V. receivers. We are able to see the picture as well as hear the sound together on the T.V. sets. Color T.V. gives the greatest reality to the pictures. This is possible with the help of special color tubes and fluorescent screen.
T.V has now become a boon for mass communication. It is a more effective media than all other available mass media techniques. In India an estimated 65 million homes television sets covering a population of about 400 million people. Besides Doordarshan, many other private T.V. channels have come up and are doing very well. The T.V. can now reach nooks and corners within seconds. T.V. is almost replacing the cinema as a medium of entertainment. Advertisements, educational programmes relating to Open University, tele-school programmes, and special programmes for ryots and labours which are being carried by radio, are now a regular feature in T.V. telecasts too. Closed circuit T.V. runs with the help of wires, and is useful for classroom programmes. Still radio has its own advantages. Both can co-exist and serve society.