Activity 8

Procedure

• Gather these items from your Optics Kit:
  • the three colored filters

• Gather these items from your home or workplace:
  • three flashlights
  • a friend
  • a light bulb (40 watts or higher)

• Spectrometer. Look at a bright light bulb through your spectrometer with the slits toward the light bulb. (DON'T LOOK AT THE SUN). You will note the spectrum extends from the blue (~400 nm) to the red (~700 nm). Use the red, blue, and green plastic filters in your optics kit and place each in turn across the entrance slit. Note which colors are transmitted and which are blocked.
  
• This project is carried out in Lab One, Module A-8 or you can use the spectrometer in Week Four Activity.

White light can be made from three colored lights

• Computer Monitor. Take the high power magnifier from the Optics Kit (lens B) and observe the colors of the patterns on a computer monitor or TV screen. The dot patterns (arrays of colored circles or rectangles used by different screen manufacturers) are colored red, blue, or green. When lit they produce the full range of colors seen on your monitor. Use the B lens on the Patterns in Nature header to see the transition in color patterns from the "green" Patterns to the "red" Nature.

• Projection TV. Just observe the light sources on a projection system (large screen TV, classroom computer projectors such as Proxima). You will find that the three light sources are red, green, and blue. If you are in a science museum (Arizona Science Center, for example) that features colored shadows, you will also note that the light sources are red, green, and blue.

• Flashlights and Filters. For this project you need to go beyond the items provided in the Optics Kit: 3 flashlights and a friend. Tape the 3 filters (red, blue, and green) on the lens cover of the flashlight and project the three sources (R, B, and G) on a white wall. The overlapping of the three sources produces white (R+G+B=W). If two sources overlap, you obtain other colors:

  		Red + Green = Yellow
  		Green + Blue = Cyan
  		Red + Blue = Magenta

• Color Printing. Printers use four plates (four-color printing) when making colored pages for a book or magazine. The four colors are yellow, cyan, magenta, and black. These colors very loosely are called yellow, blue or cyan blue, and red or magenta red. Use the "B" lens in your Optics Kit to look at the color prints in a book or magazine. The colors are produced by dots of yellow, cyan, and magenta.

• Two color white. This is a reminder that white can be produced by two colors as well as three colors and the full spectrum discussed above. Two colors that give white when added together are called complementary colors. Blue and yellow, cyan and red, as well as magenta and green are complementary colors. All 3 pairs can produce white.

To read more about color and light go to the Color and Light Readings

To read about light sources go to the Sources of Light Readings

To read about color theory go to the Composition of Color Readings

To read more about polarized light and polarizers go to the Polarized Light Readings