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This activity includes several stations representing different types of light.
For each station there is a source--the thing that produces the light--and a
detector--the thing that allows you to know the light is there.
The source for the first station
is the flashlight, which produces visible light. We detect this naturally with
our own eyes. The second type of light is ultraviolet.
The source is a small black light. As you can see it also
produces a small amount of purple light, but since we can see that, it's visible
light, not ultraviolet. The best detector for the ultraviolet
portion of the light is an invisible ink pen. Anything drawn with such a
pen can only be seen if ultraviolet light is present. Another
detector option is UV reactive beads, which only change color when
exposed to ultraviolet light. The type of light in station
three is infrared. The source in this case is a remote control.
There are two possible detectors for this station. Either a simple detection
circuit, which you can see being built in another one of our videos, or a camera-
phone or digital camera without IR blocking features. In the
case of the camera when you point the remote at the lens and press a button, you will be able
to see a light on the view screen, even though you can't see one with your eyes.
With the circuit, you point the remote at the solar cell. Pressing buttons creates
a noise in the amplifier speaker. The final
station is also infrared light, but this time the source is a heat lamp.
The detector in this case is our own skin, which will feel heat
in the presence of this infrared light. Like with the ultraviolet station,
remember that the red glow that you see is visible light, not infrared.
In this activity, we want to test various types of materials against
each type of light to see if they are transmitters, meaning they allow the light to
pass through, or shields, meaning they block the light.
We do this by holding our sheet of materials between the source and the detector
and testing for whether the particular type of light has made it through. Be
consistent in your methods, and remember that the red and purple glows are not what we are looking for.
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