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