When you watch a movie, what you actually see are many still pictures flashing by quickly. This is true of TV as well. Many still pictures are broadcast from the station, and they appear on your set so fast that they seem to be moving.
But these pictures are not sent out and picked up as complete pictures. Instead, each picture is taken apart, sent out via electrical waves, and finally put back together in your set. Here’s how it works.
At the TV studio, a camera focuses on a scene. Light reflected from that scene enters the camera’s lens and falls on a target screen inside a large tube. Since every picture is made up of a pattern of bright and dark areas, it hits the target screen with these bright and dark areas.
An electron gun inside the camera moves across the screen in a line from left to right, and from one line to the next from top to bottom. This process, called scanning, changes the bright and dark areas of the pattern into electrical waves. These waves, or signals, are then sent out through the air.
Meanwhile, your home TV set has an antenna which picks up waves from all programs sent out. The tuner on your set chooses the wave length of the channel you want to watch from all the rest of the waves. An electron gun in your set shoots the signals from that program across the screen, again from left to right and from top to bottom. In this way, it recreates the original pattern of the pictures that was sent by the TV camera at the station.
The screen on your set is coated with a fluorescent material called phosphor. The phosphor glows when it is hit by the electrons, either brighter or darker depending on the strength or weakness of the electronic beam.
The sound that goes with the TV picture is sent out in waves much like the way radio works.
In the United States, 99 out of every 100 people have TV sets!