Science Project:

Light Absorption and Color Filters

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A yellow color filter will let through only yellow and absorb all other colors. So when blue light is allowed through a blue filter onto a blue object, the object will still reflect blue and therefore appear blue. But when blue light from a blue filter hits a red object, the blue will be absorbed and no light will be reflected, giving the object an appearance of being black.

blue filter

Materials

  • Flashlight
  • Red, blue, and green construction paper
  • See-through colored cellophane paper
  • Camera filters in red, blue and green
  • Masking tape or a rubber band

Research Questions

  • Why did the papers look white, red, blue, and green (respectively)in white light?
  • How did the filters affect the white flashlight beam?
  • Why did theyellow and green papers seem to lose their color when red light was shined on them?

Procedure

  1. Darken the room as much as possible.
  2. Turn on the flashlight and aim it at the white paper. Observe and record the color of the paper in the data table.
  3. Repeat step 2 with the red, blue, and green pieces of paper.
  4. Place the red filter in front of the beam of the flash light as shown usingtape or a rubber band to secure the cellophane paper filter. Shine the filtered beam on the white, red, blue, and green papers and record the colors seen.
  5. Repeat using the blue filter and then the green filter. After each test,record the results.

flashlight

Filter

Paper
None
Red
Green
Blue
White
Red
Blue
Green

Digging Deeper

Place a filter in front of the light source. Combine two colored filters. Now combine three colors. Experiment with many different combinations.

Author: Michael Calhoun
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