Fun with Light and Color

Many students are taught in art classes that the 3 PRIMARY COLORS are:

______, ______, and ______.

From our own experiences with paint and/or crayons, we know that mixing different amounts of these 3 colors will produce other colors. For example,

Red and yellow liquids combine to form ______liquid,

Red and Blue liquids combine to form ______liquid,

BLUE and YELLOW liquids combine to form ______liquid, and

Blue, yellow, and red liquids combine to form ______liquid.

Many do not know that mixing colors of light is quite different from mixing colors of paint.

To begin with, the 3 primary colors of light are not red, blue, and yellow, but rather red, blue, and green. These 3 colors, or Frequencies, of light combine in different ways than do colors of paint. Believe it or not,

Red and Green light combine to form ______light,

Red and Blue light combine to form ______light,

BLUE and Green light combine to form ______light, and

Blue, GReen, and red light combine to form ______light.

Isaac Newton was perhaps the first person known to separate white light into its component colors of ______, ______, ______, ______, ______, and ______. To do this, he used two prisms - one to separate light into its component colors, and the other to recombine them into white light. This method of separating light into its component colors uses the property of light known as refraction.

Another way to separate any light into its component colors is through properties of light known as diffraction and interference. A simple spectroscope allows light to pass through a diffraction grating in such a way that the colors making up that light become known through these two processes.

Learn more about mixing light and color by viewing these simulations on the World Wide Web:

http://www.physicslessons.com/exp16b.htm

http://www.physicslessons.com/exp18b.htm

http://www.physicslessons.com/exp19b.htm

Make your own spectroscope

Materials:

hollow tube (paper towel roll, bamboo, toilet paper roll, etc…), old compact disk, scissors, tape, card stock, exacto knife or razor blade, marker

Procedure:

1. Place one end of your tube on the card stock and trace around the circle. (You may want to cut “flaps” around the disk for connection purposes.)

2. Use scissors to carefully cut this circle out of the card stock.

3. now use the razor blade or exacto knife to carefully cut a narrow vertical slit in the card stock circle. This slit should be about 1-2 centimeters long and 1-2 millimeters wide.

4. Place this slit circle on one end of the tube and tape it into place.

5. Now place the other end of the tube on the compact disk and trace around the circle with the marker.

6. Use scissors to carefully cut this plastic circle out of the compact disk.

7. Use tape to pull the metallic covering off the top of the compact disk until it becomes totally transparent.

8. Place the compact disk circle on the other end of the tube and hold it into place. Do not tape it at this time.

9. While holding the tube so that the slit is vertically oriented, look through the compact disk end of the tube at a distant light.

10. Keep the slit circle vertical and rotate the compact disk circle until you see vertical color bands on both the right and left sides of the vertical slit.

11. Once you have it properly oriented, tape the compact disk end in place.

12. Look at various light sources and determine the colors of light comprising each source of light. Most incandescent and fluorescent bulbs contain all colors of the spectrum, but other gas-filled tubes contain only colors that are characteristic of the gases.

Label each color of light seen when looking at a “white” light source.