Mike Shearn, age 11, of Houston, Texas, for his question:

Exactlv how does TV work?

Television is perhaps the most complicated system of communications. In order to master it down to all its exact details you need a grounding in several sciences and some specialized training in mechanics. However, like most workable systems, it is based on a few simple principles.

Andy cannot explain the exact details of television in just a few paragraphs. He has only enough space to outline the basic factors that make it work. It so happens that this is a good way to start tackling a complicated system, such as TV. First get an outline of the basic facts in your head. Note what forms of energy are used to do the job. List what these forces can and cannot do. As you grasp these basic factors, you will see for yourself how these natural forces have to be helped, adapted and modified to do the special work needed for the job.

The natural forces used to make television work are radio and electricity. High frequency radio waves do the big job of carrying the communication from the broadcasting stations to the receiving sets. Electricity is used to do the detailed job of adding sounds and pictures to the carrier waves. Radio is a form of electromagnetic energy. It travels at the speed of light, 186,000 miles a second. Also like light, it fans out from its source in straight lines. Electricity is the motion of electrons and electrons are negative particles that orbit the nucleus of the atom.

The electromagnetic energy of radio is silent and invisible. Its speed makes it a splendid vehicles for carrying messages. But some very complicated electrical tampering is needed to add the sounds and pictures to the silent and invisible radio carrier waves,

The basic carrier waves are created and broadcast by powerful electric current in the station's antenna. They cannot, of course, tote along TV in the forms of sounds and pictures. But they can be altered by electrical impulses to carry an assortment of coded signals. These signals are added to the basic carrier waves by electronic tampering at the TV studio. They are broadcast, silently and invisibly, as slight changes in the carrier waves. They are decoded back into sounds and pictures by more electronic tampering

All this elaborate electronic tampering is done in stages by iconoscopes, microphones and other tricky gadgets. Television was not mastered until the details of these electronic instruments were perfected. At the broadcasting studio, the sights and sounds of a TV show are translated into an assortment of weak and strong electrical impulses. These impulses are arranged in coded patterns and merged with the carrier waves fanning out from the station antenna. Your TV antenna traps the carrier waves, sifts out the coded signals and relays them to your receiving set. Electronic gadgets in your TV set translate the coded patterns back into copies of the sights and sounds happening in the station studio.

The broadcasting antenna is powered by high frequency alternating current. If the broadcast has a frequency of, for example, 760 kilocycles, the electrons in the current are jogging back and forth 760,000 times per second. This vibration broadcasts the spreading radio carrier waves. You tune your receiving set to pick up the special frequency used by your favorite broadcasting station. Your set decodes some of its concealed signals into sounds and scans others onto your screen at the rate of 30 complete pictures per second.