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Music

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Narrator: For this activity, I'm going to walk you through how to turn a paper towel

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tube into a spectroscope. You will need a paper towel tube,

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two roughly square pieces of aluminum foil, two strips of aluminum foil, 

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a piece of diffraction grating, a pair of scissors, and some tape.

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We will start by constructing the end that goes up to your eye.

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For this end, you will need one of the aluminum foil squares.

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Fold it into quarters and cut of the corner where all the folds meet. This gives us

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the hole in the middle of the piece of foil when everything is unfolded. The diffraction

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grating, which looks like a piece of clear plastic with a rainbow sheen to it,

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is going to be taped over this hole, so the hole should be just a little bit smaller than the

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piece of diffraction grating. Be very careful to touch the diffraction grating

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as little as possible so you don't leave fingerprints on it. Tape the edges so that you're

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still able to see through the grating. Take the

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whole foil square and wrap it around one end of the paper towel tube so the piece of diffraction

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grating is centered over the tube end. It is more structurally stable if you

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put the tape on the inside. You can tape this into place immediately.

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Music

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Next we will construct the other end of the spectroscope. Take the other

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aluminum foil square and cut a hole in the center of it in the same way as before.

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Now take each of the strips of aluminum foil,

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and fold them lengthwise, taking care to give them a nice, sharp crease.

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Place them over the foil square, with the creased edges facing each other to

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create an open slit. The size of the slit should be about the thickness of a coin.

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Tape the two strips in place, keeping them nice and parallel.

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Music

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This foil square can now wrapped around the other end of the paper towel tube in the same

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way as before, but this time, do not tape it into place right away.

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When you look into your spectroscope, remember that it's the diffraction grating

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end that goes up to your eye. When you point your spectroscope at a light source

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you should be able to see a spectrum on the walls of the tube. While looking at a light

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source that produces a spectrum, rather than a continuous rainbow,

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rotate the slit end, which you have left untaped. You should see the

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spectrum change shape, going from a long, thin smear of color to a broad spectrum

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with clear lines in it, and back again. Find the point where the spectrum is as

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thick as you can make it, and all of the individual lines are clear and straight.

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When you have found this point, you can tape the slit end in place.

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Music