WEBVTT FILE

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Music

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This activity includes several stations representing different types of light.

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For each station there is a source--the thing that produces the light--and a

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detector--the thing that allows you to know the light is there.

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The source for the first station

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is the flashlight, which produces visible light. We detect this naturally with

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our own eyes. The second type of light is ultraviolet.

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The source is a small black light. As you can see it also

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produces a small amount of purple light, but since we can see that, it's visible

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light, not ultraviolet. The best detector for the ultraviolet

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portion of the light is an invisible ink pen. Anything drawn with such a

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pen can only be seen if ultraviolet light is present. Another

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detector option is UV reactive beads, which only change color when

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exposed to ultraviolet light. The type of light in station

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three is infrared. The source in this case is a remote control.

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There are two possible detectors for this station. Either a simple detection

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circuit, which you can see being built in another one of our videos, or a camera-

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phone or digital camera without IR blocking features. In the

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case of the camera when you point the remote at the lens and press a button, you will be able

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to see a light on the view screen, even though you can't see one with your eyes.

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With the circuit, you point the remote at the solar cell. Pressing buttons creates

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a noise in the amplifier speaker. The final

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station is also infrared light, but this time the source is a heat lamp.

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The detector in this case is our own skin, which will feel heat

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in the presence of this infrared light. Like with the ultraviolet station,

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remember that the red glow that you see is visible light, not infrared.

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In this activity, we want to test various types of materials against

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each type of light to see if they are transmitters, meaning they allow the light to

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pass through, or shields, meaning they block the light.

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We do this by holding our sheet of materials between the source and the detector

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and testing for whether the particular type of light has made it through. Be

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consistent in your methods, and remember that the red and purple glows are not what we are looking for.

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Music