http://www.ck12.org Chapter 5. Energy
5.53 Color
- Relate the wavelength of visible light to its color.
- Describe how a prism separates visible light into its different colors.
- Explain why objects appear to be certain colors to the human eye.
- Identify the primary and secondary colors of light.
- Define pigment, and list primary pigment colors.
This rainbow contains all the colors that you can see in the land below it—the yellow of the hills, the green of the
leaves and grasses. It contains other colors as well. In fact, a rainbow contains all of the colors of visible light.
Wavelength and Color
Visible light is light that has wavelengths that can be detected by the human eye. The wavelength of visible light
determines the color that the light appears. As you can see in theFigure5.114, light with the longest wavelength
appears red, and light with the shortest wavelength appears violet. In between are all the other colors of light that
we can see. Only seven main colors of light are actually represented in the diagram.
Separating Colors of Light
A prism, like the one in theFigure5.115, can be used to separate visible light into its different colors. A prism is
a pyramid-shaped object made of transparent matter, usually clear glass or plastic. Matter that is transparent allows
light to pass through it. A prism transmits light but slows it down. When light passes from air to the glass of the
prism, the change in speed causes the light to change direction and bend. Different wavelengths of light bend at
different angles. This makes the beam of light separate into light of different wavelengths. What we see is a rainbow
of colors. For an animated version of the prism below, go to this URL: http://en.wikipedia.org/wiki/File:Light_disp
ersion_conceptual_waves.gif