How Does a Television Work?

Television has become a major part of life for millions of people. It has been around in one form or another for more than a century. In its most basic form a television is a piece of equipment that takes one form of energy and converts it into another form of energy – the visible and audible signals on our receiver.

The word “television” explains a lot about what this device does. It shows us pictures (vision) based on information sent from a distant location. The two parts of the word are “tele” from the Greek word meaning “far” and “vision,” which means “to see.”

According to the dictionary definition, television is “the action of seeing by means of Hertzian waves or otherwise, what is existing or happening at a place concealed or distant from the observer’s eyes” [OED]; in theoretical discussions about sending images by radio transmission, formed in English or borrowed from Fr. télévision, from tele- + vision. Other proposals for the name of this then-hypothetical technology were telephote (1880) and televista (1904). The technology was developed in the 1920s and ’30s. Nativized in Ger. as Fernsehen.”

Basic Science

Inventor/scientist Michael Faraday was able to show how closely related light and electricity were (1830s), a demonstration that led to practical uses for sending electronic signal patterns consisting of light and sound data then receiving those signals and converting them into visible and audible form.

The first version of television depended on mechanical disks and other apparatus to turn electrical signals into visible information. In the 20th century scientists came up with the cathode-ray tube, moving it from its original purpose (X-rays) to receiving images. In fact, a German engineer learned that he could manipulate the stream of electrons (the signal) with a separate magnetic field.

Some of the key parts of a television receiver are the electron beam, the pixels or dots of information and of course, the tube that was the original television “screen.” The electronic signal is sent through waves in the air or through wires to the receiver. Different “channels” carry information at different frequencies so that a television set can pick up dozens of channels. We select which frequency/signal we are going to watch.

Newer televisions display the information on liquid crystal display (LCD) or plasma screens, rather than on the original cathode ray tube. Television signals are now sent in three ways: broadcast – signals are waves of varying frequencies sent through the air; satellite – original information is directed at an orbiting satellite and then redirected to our receivers; cable – digital information is sent through wires and converted to visible and audio information we see and hear.