• Question: How do TVs work? Is it something to do with the signal sending different waves for different things?

    Asked by 235689jack to Amy, Karen, Sarah, Vijay, Will on 18 Jun 2012. This question was also asked by nilokoko.
    • Photo: Amy Birch

      Amy Birch answered on 18 Jun 2012:

      Hi jack,

      Tvs work by showing us still images (like pictures) very fast, about 30 times a second and every picture is slightly different so that it looks like things are moving on the screen. The pictures are made with tiny dots or stripes of light that are usually either blue, green or red so that all the colour combinations can be created.

      The signal is usually from a cathode-ray tube at the back of the tv, which shoots electrons at the back of the tv screen and hit tiny red, blue or green points on the screen to create the image. Plasma tvs are slightly different, they are too skinny for cathode-ray tubes so use tiny compartments filled with gas. The electrical signal from satellite/cable/antenna charges the gas and creates energy that lights up the red, green or blue spots on the tv.

      Hope this answers your question! 🙂

    • Photo: Sarah Martin

      Sarah Martin answered on 20 Jun 2012:

      Hi 235689jack!

      TVs actually work by tricking our eyes and our brains! The screens show us many still images, like pictures. They change very quickly, often 30 times every second! With pictures moving so fast, and each picture being just a little bit different, our eyes are tricked into thinking we’re actually seeing something moving. Really we’re just seeing pictures changing really fast!
      The picture is actually made with light! Thousands of tiny dots or stripes of light are used to make a full picture on our TV screens. There are three primary colors of light that are used: red, green, and blue. By using those three colors in different combinations, our TVs can make any color we can think of!

      So how does a TV know which colors to display I hear you ask? Well, a video signal comes into the TV from antennas, satellite dishes, cable or other TV services. It’s an electrical signal that tells the TV’s speakers what sounds to make, and it tells the screen which colors of light it should show. Many TVs use what’s called a cathode-ray tube, which actually shoots beams of energy (electrons) at the backs of our TV screens. These beams are so precise that they can hit just one tiny red, green, or blue point on the screen. When they hit, a small part of the TV screen shines as one of those colors! The rays of energy zigzag across the screen, lighting up different colors faster than our brains can notice. We just see a full picture on the TV!

      🙂 Sarah

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