Can a Visible Light Outshine Infrared Radiation?
Grade Levels: 5 - 10
In this comparative project, you'll be looking at two types of electromagnetic radiation.
Electromagnetic radiation is energy that travels in transverse waves, and is measured in wavelengths.
A wavelength is measured from the top of one crest to the top of the next crest. The shorter the wavelength is, the more energy it contains.
Gamma rays have the shortest wavelengths and radio waves have the longest wavelengths. Just as the names imply, these waves include magnetic and electrical components.
Electromagnetic radiation includes forms of energy ranging from visible light to radio waves, microwaves, and gamma rays.
These different energies are part of the electromagnetic spectrum, of which only a very small part is the visible spectrum of light containing all the colors in the rainbow.
The infrared radiation that comes from a remote control device, such as the TV clicker, has a larger wavelength than visible light, although we can't see it with the naked eye. On the other side of visible light is ultraviolet radiation from the sun. That's the stuff that causes sunburn and skin cancer.
These wavelengths are shorter, and therefore they have more energy than infrared radiation or visible light. Again though, you can't see that type of radiation with the naked eye.
For this experiment, you'll use an ordinary flashlight, a TV remote control and a few variables such as a glass of water, a glass of milk, sheets of paper, and a piece of plywood that's as large as your TV screen.
To compare these two types of radiation, you'll need to set up a testing area in a room that contains a television.
Place a piece of tape on the floor 8 feet (2.4 meters) away from the TV. This is where you'll stand to conduct each test of this experiment.
Darken the room as much as possible, and make sure the TV is turned off.
You'll conduct the following series of tests separately for the remote control-the source of infrared radiation-and the flashlight-the source of visible light.
Conduct each test with the flashlight first, recording your observations in a journal. Then perform the same test, using the remote control. Again, record your observations.
All tests are performed with you standing at the 8-feet tape mark.
- Test 1: Shine the flashlight at the TV screen and record what you see. Repeat with the remote control.
- Test 2: Hold a glass of water directly in front of each device and record your observations when you turn each of them on.
- Test 3: Hold a glass of milk in front of each, turn each one on, and record your observations.
- How do the milk and water affect how we see the light? Can the TV still be turned on if the radiation is passing through glass and a liquid?
- Test 4: Hold a piece of paper in front of each device and turn them on. How many pieces of paper are needed to completely block the visible light from shining onto the TV screen? How many pieces of paper are needed to prevent the infrared radiation from penetrating through the paper so the TV won't turn on?
- Test 5: Have someone hold the piece of plywood directly in front of the TV screen. Make sure your helper is to the side of the plywood, not in front of it. Turn on each light. Record what you see.
- Test 6: Continue to decrease the distance between the plywood and the flashlight/remote control in 2-foot increments. Turn on the device and record your observations.
As you should have been able to observe, not all radiation is created equal. Can you think of other ways to test the properties of these two types of radiation? What other variables could you use? How far away can you be from the TV and still turn it on with the remote control? What is its working range? Can you still see the light from the flashlight on the TV screen at that distance?
Create a chart that shows your observations from the tests. What could account for the differences? Do some research before you begin this project to gain a better understanding of electromagnetic radiation.
Excerpted from The Complete Idiot's Guide to Science Fair Projects © 2003 by Nancy K. O'Leary and Susan Shelly. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.
To order this book visit the Idiot's Guide website or call 1-800-253-6476.
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