Colors of Light
Visible light from the sun is colorless. However, if you bend visible light by passing it
through a prism, it produces a “rainbow” of light of different colors (Figure20.19). Why
does this happen? Different colors of visible light have slightly different wavelengths. Light
of different wavelengths bends by different degrees when it passes through a prism. This
separates visible light into all of its colors.
Figure 20.19: A prism bends white light to create a “rainbow” of red, orange, yellow, green,
blue, indigo, and violet light. ( 31 )
Light and Vision
Except for objects that give off their own light, we don’t see things just because light strikes
them. We see things because light strikes them and then reflects, or bounces back, from
their surface. What we see is the reflected light.
Some things reflect all the light that strikes them. These things appear white. Some things
do not reflect any light. Instead, they absorb all the light that strikes them. These things
appear black. Other things, like the beads inFigure20.20, reflect just one wavelength of
light. Whatever wavelength they reflect is the color we see. For example, beads that reflect
only red light look red to us.
Lenses and Vision Correction
You probably know people that need eyeglasses or contact lenses to see clearly. Maybe you
need them yourself. Lenses are used to correct vision problems. Two of the most common