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How Do Televisions Work?
How does The Oprah Show end up on the television screen in your house? Marshall Brain knows! First, a video camera takes Oprah's picture and breaks it up into about a quarter of a million tiny little dots called pixels. Each one of these dots has a color and a place on the screen. The camera converts this series of dots into an electrical signal that is then sent to a satellite dish about three miles from the studio. The satellite dish converts the electrical signal into radio waves and beams them up into space to a satellite 22,000 miles away. From there, the signal can be directed to any place on the planet—from cable companies to the dish on your roof—where it's turned back into an electrical signal.
The signal is still a bunch of dots, but your TV puts them all back together to make a picture. Something called an electron gun, inside your television, sprays all those dots onto your TV screen in the same order they were originally sent out. In this way an entire picture is created.
This entire process happens 30 times a second—that's why the images seem to move!