Take-Home Activity: Color My World

Discover how a television creates multi-colored images by using only three primary colors.

Turn on a color television set and the screen lights up with tiny red, blue, and green dots. Because the dots are close together and change quickly, our brain mixes these colors together to produce an incredible assortment of colors. Mix colored lights together and see what happens.

Materials

1. red, blue, and green cellophane
2. 3 standard flashlights
3. a large sheet of white paper or fabric taped to a wall
4. A friend (or parent!)
5. Tape

Directions

1. Tape the 3 pieces of celophane over each of the 3 flashlights.

2. Tape a piece of white paper to the wall.

3. Have you and your friend hold the different-colored spotlights so that they are all aimed at a central spot on your screen about six feet back from the screen.

4. Make the room as dark as possible and turn on the spotlights, adjusting them so that the combination of their light produces a whitish color on the screen.

5. Turn off the red spotlight. What color is evident now? Repeat by turning off the blue and green spots while leaving the others on. How many different colors can you get from only three colored lights?

6.Stand about halfway between the screen and the spots and wave your hands back and forth. What happens to the colors on the screen? Note: The same procedure can be done with students holding flashlights and aiming the beams at a central point on the screen. However, it may be harder to create the colored shadows using this method.

Questions

1. Why do the colors on the projection screen change when you move your body in front of them? How might this relate to electron guns in a television set turning on and off?

2. Television isn't the only medium that uses color-blending to create full-color images. How does this same principle relate to the printing of color pictures in newspapers, or the processing of satellite images of the earth?

Notes

Television flashes a series of images so fast that your eye sees them as one moving image. Make a flickerbook to help understand this idea. Take a small pad of paper stapled together at one end. Draw a series of simple images, such as a seed growing. Working from the last page to the first, draw the images with incremental differences. When done, flip through your book from the last page to the first.

Take a magnifying glass and look closely at a show playing on your television set. Do you see the phosphor dots? Where else might you find the concept of tiny dots forming images? Which of your examples uses the colors of light and which uses the colors of pigment?