NetLogo User Community Models
by Ed Hazzard (Submitted: 09/19/2007)
WHAT IS IT?
This model looks at the absorption of light by colored filters. In this case the filter is a chamber filled with gas molecules that absorb specific wavelengths of light.
HOW IT WORKS
Turtles representing photons are created and directed at a surface. Initially they are a random mixture of red, green, and blue, using the RGB system. When they hit the surface, you can choose which ones are absorbed. All the others pass through the filter.
The circle to the right displays the color of the average RGB values of all the photons that make it through the filter.
HOW TO USE IT
Setup and run the model. Try absorbing different colors. Try absorbing everything. Does the filtered color match your expectations?
THINGS TO NOTICE
THINGS TO TRY
EXTENDING THE MODEL
This model deals with only three colors and their mixtures. Try refining the model to deal with a larger range of colors and absorptions.
This model makes use of the "rgb R G B" primitive, which converts an RGB value (each number ranging from 0 to 1) to a NetLogo color. For instance, the color red is
If the gas absorbs red, it changes the first number to 0. That is, RGB 1 0 0 becomes RGB 0 0 0, which is black. Knowing these rules, can you figure out what absorption does to each color?
CREDITS AND REFERENCES
This model was created by Ed Hazzard at the Concord Consortium as part of an activity for an NSF-funded project called ITSI (Information Technology in Science Instruction). See http://itsi.concord.org.
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