FREE Spectroscope!

CHEAP IS GOOD: You can have your kids make a working demo spectroscope FOR FREE! REAL spectroscopes come in handy in Honors and AP Fizzix. However, for a demonstration and with a lack of a few thousand dollars, this demo version is great to show how one works and to investigate the properties of visible light. Here's what to do;

VAST Supply List:

  1. Some paper. Oaktag works good, but regular WHITE construction paper works fine.
  2. 1 CD - Compact Disc. My personal preference is Phil Collins or TranSiberian Orchestra, but any personal musical preference will do. This can be done for free seeing as how America Online has provided an inexhausible supply of AOL CD's. Have kids bring in those 39 extra copies they've received in the mail or just pick up a handfull of FREE AOL V6 CD's at your local convenience store. Like I said, Free is GOOD!
  3. Scotch tape.
Supplies
Now that you have spent hours preparing all these items, follow these construction steps. OVERVIEW; All you are going to do is make a paper tube, like a coffee can, with the CD at one end, a lid with a small slit, or 'top' end, to allow light in, and a 'viewing slot' in the bottom of the cylinder side near the CD to view the spectrum produced.

  1. Either cut from LARGE paper stock or create with smaller pieces ONE piece of paper measuring 4 1/4" x 19". This will be the 'can' part of the spectroscope. Cut a 'viewing' notch measuring 1/4" wide x 1 1/4" high at one long edge around the center of this long strip.
    Slit 1
  2. Now, comes the manual dexterity portion of our workout... Wrap this 19" long piece of paper around your FREE CD. (SAFETY NOTE: Make sure you are alone and out of shouting distance from small children. The terms you are about to throw from your mouth in frustration will make any sailor blush and should not be heard by small humans!) Make sure the plain side, the non-printed side, of the CD is inside the cylinder. Tape the paper so it forms a snug can around the CD like the CD is the bottom of a soup can. Tape the CD in place at the bottom of the cylinder making sure the viewing notch is also at the bottom of the can so you can clearly see into the CD. Tape only the 'bottom' of the CD; the part that has writing on it and is 'outside' the can. Tape on the encoded side can interfere with the spectral lines to be produced.
    Can 1
  3. Now, if you are not trained in the proper use of scissors and have trouble coloring in the lines (like yours truely...), cut out a paper square 5 1/2" by 5 1/2". This will serve as the 'top' of the can. Cut a slit about 2 mm wide (You like my random switching of unit systems?) and perpendicular to one of the sides of the square. Center the slit on one this side of the square and make it 1/2 inch from the edge. Now, place the top on your spectroscope. Make sure the slit is directly over the notch in the tube and perpendicular to it. (See pictures). Tape the top onto the tube.
    Lid

    If you are scissor and construction paper proficient, you can do the same as mentioned above, but make the top more aesthetically pleasing by making it circular. I've attempted this, and failed miserably. My kids seem to be able to do it at will. (The little pests...)

Final Spec
Note the spectrum shot here.

Now, why did you bother doing all this? Shine different kinds of light thru the top slit and look thru the viewing slot at the bottom. You will see clearly defined "rainbows" or spectral batches on the CD. Shine several different kinds of light and the kids notice a telltale "signature" spectrum for each kind of light. Suggest using incandecent, fluorescent, halogen, sun. If you have a gymnasium in your building, take a mini-fieldtrip to the gym to allow viewing of the gym lights. They are usually Mercury Vapor lamps that have a very distinct and incomplete spectrum. Also, have the kids note colors of their shirts and SKIN before entering the gym and compare to the apparent colors under the gym lights. Neat differences.

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