Produced exclusively for Newspapers In Education

Despite his unforgettable name, you've probably never heard of Philo T. Farnsworth—which is really a shame, since he helped invent TV. And he did it when he was just a kid. Farnsworth grew up on a farm in Idaho, but loved electronics. In 1921, when he was 14, two new inventions caught his eye: the photoelectric cell, which turns light into electrical signals, and the cathode ray tube, which turns electrical signals back into light.

Farnsworth wanted to use these inventions together. He thought he could change a picture into an electrical signal, send the signal across a wire, and then reassemble the picture someplace else. He had it all figured out—except for the last step.

One day, while plowing a field, he suddenly realized that he could "build up" an electronic image by drawing lots of back-and-forth lines of light—like the rows of soil he was plowing. In 1927, Farnsworth moved to San Francisco to test his ideas, and built the first successful electronic TV system here.

Today, most TVs still work the way Farnsworth envisioned, making pictures by drawing thousands of dotted lines of light back and forth across the screen.


Dot-to-Dot Pictures
To do this activity, you'll need:
  • newspaper pictures
  • a magnifying glass
  • a turned-on TV
  • a few drops of water
  • Use your magnifying glass to look closely at a photo in the newspaper. See all the little dots?

    Now dip your fingers in the water and spray a few drops onto a TV screen. The drops will act like tiny magnifying lenses. Look closely and you'll see that the picture on the TV is made up of dots, too.

    What's going on?

    Even though your eyes see patterns of dots, your brain has no trouble recognizing them as pictures. That's because your brain is always trying make sense of the things you see. As long as the dots are the right size and spacing, your brain will be able to blend them together and recognize the picture they make.

    Pictures made from dots don't just show up in newspapers and on TV. Check out the pictures in books, magazines, and even on movie and computer screens.




    2001 The Exploratorium