http://www.ck12.org Chapter 5. Energy
A transparent or translucent material, such as window glass, transmits some or all of the light that strikes it. This
means that the light passes through the material rather than being reflected by it. In this case, we see the material
because of the transmitted light. Therefore, the wavelength of the transmitted light determines the color that the
object appears. Look at the beautiful stained glass windows in theFigure5.117. The different colors of glass
transmit light of different colors.
FIGURE 5.117
The color of light that strikes an object may also affect the color that the object appears. For example, if only blue
light strikes green leaves, the blue light is absorbed and no light is reflected.
Q:What color do you see if an object absorbs all of the light that strikes it?
A:When all of the light is absorbed, none is reflected, so the object looks black. But black isn’t a color of light.
Black is the absence of light.
The Colors We See
The human eye can distinguish only red, green, and blue light. These three colors are called theprimary colorsof
light. All other colors of light can be created by combining the primary colors. Look at the Venn diagram 5.118.
Red and green light combine to form yellow light. Red and blue light combine to form magenta light, and blue and
green light combine to form cyan light. Yellow, magenta, and cyan are called the secondary colors of light. Look at
the center of the diagram, where all three primary colors of light combine. The result is white light. You can explore
the colors of visible light and how they combine at this URL: http://www.phy.ntnu.edu.tw/oldjava/color/color_e.htm
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FIGURE 5.118
Pigments
Many objects have color because they contain pigments. Apigmentis a substance that colors materials by reflecting
light of certain wavelengths and absorbing light of other wavelengths. A very common pigment is the dark green