WEBVTT FILE

1
00:00:00.010 --> 00:00:11.070
Music

2
00:00:11.090 --> 00:00:15.150
Narrator: For this activity, I'm going to walk you through how to turn a paper towel

3
00:00:15.170 --> 00:00:19.190
tube into a spectroscope. You will need a paper towel tube,

4
00:00:19.210 --> 00:00:23.200
two roughly square pieces of aluminum foil, two strips of aluminum foil,

5
00:00:23.220 --> 00:00:27.220
a piece of diffraction grating, a pair of scissors, and some tape.

6
00:00:27.240 --> 00:00:31.280
We will start by constructing the end that goes up to your eye.

7
00:00:31.300 --> 00:00:35.310
For this end, you will need one of the aluminum foil squares.

8
00:00:35.330 --> 00:00:39.380
Fold it into quarters and cut of the corner where all the folds meet. This gives us

9
00:00:39.400 --> 00:00:43.400
the hole in the middle of the piece of foil when everything is unfolded. The diffraction

10
00:00:43.420 --> 00:00:47.420
grating, which looks like a piece of clear plastic with a rainbow sheen to it,

11
00:00:47.440 --> 00:00:51.450
is going to be taped over this hole, so the hole should be just a little bit smaller than the

12
00:00:51.470 --> 00:00:55.530
piece of diffraction grating. Be very careful to touch the diffraction grating

13
00:00:55.550 --> 00:00:59.550
as little as possible so you don't leave fingerprints on it. Tape the edges so that you're

14
00:00:59.570 --> 00:01:03.600
still able to see through the grating. Take the

15
00:01:03.620 --> 00:01:07.620
whole foil square and wrap it around one end of the paper towel tube so the piece of diffraction

16
00:01:07.640 --> 00:01:11.650
grating is centered over the tube end. It is more structurally stable if you

17
00:01:11.670 --> 00:01:15.690
put the tape on the inside. You can tape this into place immediately.

18
00:01:15.710 --> 00:01:17.720
Music

19
00:01:17.740 --> 00:01:21.740
Next we will construct the other end of the spectroscope. Take the other

20
00:01:21.760 --> 00:01:25.750
aluminum foil square and cut a hole in the center of it in the same way as before.

21
00:01:25.770 --> 00:01:29.790
Now take each of the strips of aluminum foil,

22
00:01:29.810 --> 00:01:33.820
and fold them lengthwise, taking care to give them a nice, sharp crease.

23
00:01:33.840 --> 00:01:37.860
Place them over the foil square, with the creased edges facing each other to

24
00:01:37.880 --> 00:01:41.950
create an open slit. The size of the slit should be about the thickness of a coin.

25
00:01:41.970 --> 00:01:45.990
Tape the two strips in place, keeping them nice and parallel.

26
00:01:46.010 --> 00:01:49.020
Music

27
00:01:49.040 --> 00:01:53.060
This foil square can now wrapped around the other end of the paper towel tube in the same

28
00:01:53.080 --> 00:01:57.100
way as before, but this time, do not tape it into place right away.

29
00:01:57.120 --> 00:02:01.120
When you look into your spectroscope, remember that it's the diffraction grating

30
00:02:01.140 --> 00:02:05.150
end that goes up to your eye. When you point your spectroscope at a light source

31
00:02:05.170 --> 00:02:09.190
you should be able to see a spectrum on the walls of the tube. While looking at a light

32
00:02:09.210 --> 00:02:13.230
source that produces a spectrum, rather than a continuous rainbow,

33
00:02:13.250 --> 00:02:17.250
rotate the slit end, which you have left untaped. You should see the

34
00:02:17.270 --> 00:02:21.280
spectrum change shape, going from a long, thin smear of color to a broad spectrum

35
00:02:21.300 --> 00:02:25.350
with clear lines in it, and back again. Find the point where the spectrum is as

36
00:02:25.370 --> 00:02:29.360
thick as you can make it, and all of the individual lines are clear and straight.

37
00:02:29.380 --> 00:02:33.390
When you have found this point, you can tape the slit end in place.

38
00:02:33.410 --> 00:02:44.511
Music