Name __________________________________________Date __________________________Period_____
Beads of Sweat
Background Research:
Ultraviolet light (UV) is one of the invisible frequencies of light given off by the sun. It is part of the electromagnetic
spectrum and has shorter wavelengths (more energy) than violet light and a higher frequency. Over-exposure to UV light
can be harmful to many things, including humans. Its effects can be seen in faded paper, a cracked and brittle rubber hose
that has been left in the sun and a sunburn. UV light can also damage skin cells and DNA. Normal symptoms of sunburn in
humans and other animals is red skin that is hot to the touch, general fatigue and mild dizziness. Lesser amounts of UV
exposure can lead to a suntan. Excessive exposure can lead to non-malignant tumors and/or melanoma (skin cancer). In
this lab you will be exposing the beads to two different strength sunscreens and with no sunscreen to test the intensity of
the beads colors.
Problem or question: Does sunscreen provide protection from UV rays?
Hypothesis:
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Procedure:
1. Place 5 beads into a plastic zip lock bag and label the bag as control
2. Place 5 beads into a plastic zip lock bag and label it with _____________ Sunscreen. Take one drop of sunscreen
and spread it over the side of the baggie with the label on it. Give it two minutes to dry.
3. Place 5 beads into a plastic zip lock bag and label it with _____________ Sunscreen. Take one drop of sunscreen
and spread it over the side of the baggie with the label on it. Give it two minutes to dry.
4. Place the baggie on the window sill and let it sit there until we get our outdoors data. When placing your bag in
different places the side with the label should be facing up.
5. When we go outside we will place our baggies in the direct sunlight and wait a few minutes (3). After a few
minutes rate the intensity of the beads and enter it in your data table. The intensity is rated from a zero to a five.
Zero means that the beads stayed white and a five means that they turned a very bright color. Use your judgement
to assign other numbers.
6. Now place your bags in the shade and wait a few minutes (3). rate the intensity and enter it on your data table.
7. When we go inside get your baggie off the window sill and rate the intensity of the color and enter it onto your
data table.
Data Table:
Baggie type
Window intensity
Sun Intensity
Shade Intensity
Control
SPF:
SPF:
Make a bar graph of your results
Your graph will have six bars. Each type of baggie and where it was placed. For each place put 3 bars together for each baggie type
Analysis:
1. Explain your results of the experiment
2. What are your control variables?
3. What is the independent variable?
4. What is the dependent variable?
5. What is the control group in your experiment and why is it important?
6. How does UV light compare to violet light?
7. Between what two waves on the EM spectrum is UV Waves found?
8. Give two example of How UV waves are used in the real world