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Home Concept Builders Light Waves and Colors Color Pigments Help Help 6

Color Pigments - Questions 6 Help

There are three primary pigments. Each pigment is designed to absorb a single primary color of light. Cyan pigments absorb red light and reflect blue and green light. Magenta pigments absorb green light and reflect red and blue light. And yellow pigments absorb blue light and reflect red and green light.

There are two similar versions of this question. Here is one of those versions:
 

Version 1:

In two experiments, different colors of light are directed towards the same sheet of paper (of unknown color). The results of each experiment are shown. What pigment or pigments is/are in the sheet of paper?
 

There are two diagrams showing how the paper interacts with light. In each case, the color of the paper is an indicator of the light color(s) that the paper reflects. You must analyze each diagram to determine if the paper absorbs or reflects each primary color of light.

Both diagrams show a secondary color of light incident upon the paper. Secondary colors of light (like magneta light) can be thought of as being composed of two primary colors (like red light and blue light). If the paper appears as one of these colors, then that is the color the paper reflects; the other primary color is being absorbed. Analyze each diagram and determine if the paper absorbs or reflects red light, green light, and blue light.

Once you have analyzed both diagrams in this manner, you are ready to answer the question. Knowing that cyan pigments absorb red light, magenta pigments absorb green light, and yellow pigments absorb blue light will allow you to draw a conclusion regarding what pigments are in the paper. A sheet of paper that absorbs a single primary color of light contains a single primary pigment. A sheet of paper that absorbs two primary colors of light contains two primary pigments.

Try this link to The Physics Classroom Tutorial for more help with the understanding how filters interact with the incident light:

Color Subtraction

Concept Builder Teacher Notes Directions