How a Television Works

455 Words1 Page

How a Television Works

The job of a TV set is to turn the electronic signals created by TV

cameras and microphones back into pictures and sound. The TV's aerial

picks up the signals from the transmitting studios and they then

travel down a cable to the aerial socket at the back of the TV. When

you switch on the set, the sound and picture signals are separated

from each other and from the carrier waves. (The TV signal on its own

isn't powerful enough to travel very far so it is mixed with the much

more powerful carrier wave and can then travel much larger distances.)

The sound is then sent to the TV's loudspeaker. The picture signal is

split into three separate colour signals; red, blue and green. If you

look closely at a television screen you can see that the picture is

made up of lots of horizontal lines. These lines are made up of tiny

dots which glow red, blue or green. Your eye has three types of

detectors - called cones - that react to these colours differently.

There's a red cone that likes red light, a green cone that likes green

light and a blue cone that likes blue light. When any colour enters

your eye and hits these cones they send messages to your brain saying

"I'm seeing red light" or "I'm seeing green light" or eve "I'm seeing

a bit of blue and a bit of green". When the light from the dots on the

television screen enters your eye, each cone sees each colour and

sends a signal to your brain. Your brain then works out what colour it

is supposed to be seeing from these signals. The screen itself is part

of something called the picture tube. At the back of the picture tube

are three electron guns (that fire electrons rather than bullets!) one

for each colour. The electrons are shot out of the gun and hit the

screen. These dots are made of phosphor, which glows when electrons

hit it, the stronger the beam of electrons the brighter the glow.

Open Document