Transcript Prisms Lab - MR. Ahearn's Physical Science

Prisms Lab
Mr. Ahearn
2010
Introduction
A prism is a transparent optical element with
flat, polished surfaces that refract light.
• Prisms are typically made out of glass, but
can be made from any material that is
transparent to the wavelength for which they
are designed.
• A prism can be used to break light up into its
spectral colors (ROY G BIV). Prisms can also
be used to reflect light, or to split light into
components.
History
Light changes speed as it moves from one medium to another
(for example, from air into the glass of the prism). This speed
change causes the light to be refracted and to enter the new
medium at a different angle.
In Newton’s time, it was believed that white light was colorless,
and that the prism itself produced the color. Newton's
experiments convinced him that all the colors already existed
in the light.
Newton arrived at his conclusion by passing the red color from
one prism through a second prism and found the color
unchanged. From this, he concluded that the colors must
already be present in the incoming light — thus, the prism did
not create colors, but merely separated colors that are
already there. He also used a lens and a second prism to
recompose the spectrum back into white light.
Newton’s Experiment
Lab Question
What happens to visible light as it passes
through a prism?
Goals
1. Construct a prism and observe the
different colors that are produced
2. Infer how the bending of light waves
depends on their wavelength.
Materials
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Microscope slides (3)
Transparent tape
Clay
Flashlight
Water
Procedure
1. Carefully tape the 3 slides together on their
long sides so they form a long prism.
2. Place one end of the prism into a softened
piece of clay so the prism is standing
upright.
3. Fill the prism with water and put it on a table
that is against a dark wall.
4. Shine a flashlight beam through the prism
so the light becomes visible on the wall.
Conclude and Apply
1. List the order of colors you saw on the wall
2. Describe how the position of the colors on the wall
changes as you change the direction of the
flashlight beam.
3. Describe how the order of colors on the wall
changes as you change the direction of the
flashlight beam.
4. Infer which color light waves have changed
direction, or have been bent, the most after
passing through the prism. Which color has been
bent the least?
5. Infer how the bending of a light wave depends on
its wavelength.
Now go write your report!
Works Cited
Ezrailson, Cathy, Nicholas Hainen, Deborah Lillie, and Dinah Zike. Waves, Sound, and Light.
New York: Glencoe/McGraw-Hill, 2008
"Prism (optics)." Wikipedia, the Free Encyclopedia. Web. 18 Nov. 2010.
<http://en.wikipedia.org/wiki/Prism_(optics)>.