Your skin is also an excellent detector of ultraviolet (UV) radiation. When
you expose bare skin to sunlight, your skin will either turn brown (a suntan)
or red (a sunburn). These responses by your skin are a signal that the cells
under your skin are being assaulted by UV radiation. UV radiation wavelengths
are short enough to break chemical bonds in your skin tissue and over prolonged
exposure, your skin may wrinkle or skin cancer may appear.
There is a safer way to detect UV--by using UV beads. These
plastic beads contain a chemical which changes color when exposed to UV
radiation. The colors that develop depend on the wavelength of the UV radiation.
1. Place a selection of UV beads near a fluorescent light.
Do any of the beads change color? Can you get a sunburn or a tan by sitting
next to a fluorescent light?
2. Take the UV beads outside, but not into direct sunlight.
Do any beads change color? Is there UV radiation in the shade?
3. Now place the beads in direct sunlight. What do you
notice about the intensity of the beads' color?
4. Place the beads in direct sunlight and place a sheet
of thin plastic over them and note the colors. Now spread on a layer of
a commercial sun block on the plastic and note if any of the bead colors
are reduced. Try this experiment with a number of sun blocks with different
ratings. Which brand and which ratings block solar UV most effectively?
5. If you are able, take the beads to a tanning parlor
and expose them to the UV radiation from the tanning lamps. How does this
UV radiation compare to the sun's UV?
6. If you take a trip into the mountains, take the beads
along and see if there is any difference between colors at high altitudes
and at sea level.
You can purchase UV beads from:
Educational Innovations, Inc.
362 Main Avenue
Norwalk, CT 06851
Toll Free: 888-912-7474
Direct link to UV Bead page
or
Arbor Scientific
P.O. Box 2750
Ann Arbor, MI 48106-2750
Direct link to UV Bead page
Created 1997 The Exploratorium
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Regents of the University of California
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