Prism to Spectra
Name: Susan T.
How does a prism turn ordinary light into a spectrum of colors?
Ordinary white light is really made up of all the different colors combined
together. When the white light goes through the prism, each color bends to
a different angle. The prism separates the white light into all the
different colors that it is made of.
An interesting experiment can be done with three flashlights and colored
plastic you can see through. Cover one flashlight with red plastic. Cover
one with green plastic. Cover the third with blue plastic. In the dark,
shine them on a white piece of paper or a white wall. You will see a red
spot, a green spot, and a blue spot. Now, shine all three on the same place
at the same time. Make their spots overlap. You will se a much whiter
light than any of the three spots alone.
Dr. Ken Mellendorf
Illinois Central College
Very cool question. A prism is a piece of glass that refracts or ends
light. Light that we see everyday is called white light. You may already
know that white light contains all the colors of the rainbow. When white
light passes through a prism, each color of light bends at a slightly
different speed. When this happens the colors become spread out enough
that we can see a rainbow. Violet light is bent the most and red is bent
"Ordinary" white light is actually a mixture of light of all visible
wavelengths, that is, colors. When light moves from air to glass and back
to air again, it changes direction slightly with each change in material.
Going from air to glass, blue light bends the most and red bends the least.
So the rays of light of different colors that were all going the same
direction move in slightly different directions, and the spectrum of colors
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
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Update: June 2012