Color Filters

• Use the flashlight with a colored filter from the "X" envelope to shine that color onto your white surface. What do you see? Try each of the colors.

• Now add a second colored filter to the flashlight. What color shines onto your white surface?

• What does a color really filter do to light? How can you tell?

Mixing Colors

• When you mix two colors what happens? Is the resulting color brighter or darker? Is this always true?

• Predict what will happen when you use light to mix two colors. Use two flashlights with a different color filter on each. Now shine the two colors onto the same spot on your white surface. What was the result? Was the new color brighter or darker? Try every combination that you can with the three filters, but only two flashlights.

• Predict what would happen if you shined all three filters, one on each flashlight, onto the same spot of the white surface. Try it! What did you get? Why?

• What general name is given to the three colors of light shown on the filters?

The Eye

• What colors can you see? Why? Eye - color graph

What Color is the Sun?

• Is the Sun yellow? No! What color does a white piece of paper appear to be in sunlight? Yellow? White! What color is sunlight? White! So why does EVERYONE say the Sun is yellow? Scott's personal theory is that the blue sky makes the Sun look yellow.

Colored Shadows

• How many shadows does one light source make? What about two light sources?

• Use the three flashlights, each with a different color, to shine on the white surface. Put some object like a hand in front of the white board to cast a shadow on the board. How many colors do you see now? Name each of the colors that you see. How many shadows are formed? One? Three? More?

Demonstration of same effect with flood lights.

More Color Filters

• Open second envelope with additional filters.

• Put one of the new color filters over a flashlight.

• Now add either a red, blue or green colored filter to the flashlight. What color shines onto your white surface?

• Why was this effect different from what happened before?

More Mixing of Colors

• Predict what would happen if you shined all three filters from the new envelope, one on each flashlight, onto the same spot of the white surface. Try it! What did you get? Why?

• Collectively what are these three colors called?

• Reserve the Fun With Light learning center (shown above) from Lake Afton Public Observatory by calling 978-3191. The staff will present it to your class, then you and your students can experiment with the kit for two weeks. The free kit includes a strong light source, colored filters, mirrors, and a variety of lenses. Get your own filters!

The Filters used:

Primary Colors

Lee Filters: 139 Primary Green, 106 Primary Red, 071 Tokyo Blue

Complimentary Colors

Lee Filters: 116 Medium Blue-Green, 126 Mauve

Roscolux Filter: #21 Golden Amber

You can order 20" x 24" sheets of these filters from XS Lighting, 14028 West 107^th Street, Lenexa, KS 66215-2005 (913) 469-0369