Create a Simple Spectrum

Creating a spectrum (or “spectroscope”) is an educational and fun activity that allows you to see the different colors that make up a wave of light: red, orange, yellow, green, blue, violet, and indigo. Building your own spectrum will take about an hour and requires access to everyday items.[1] The spectroscope you will be making has three main parts: a viewing port made from a paper tube, a diffraction grating made from two business cards or razor blades, and a CD or DVD disk that reflects light.

Steps

Assembling the Spectrum

  1. Gather your materials. First, you will need to make sure you have all the materials to make a spectrum:
    • A cardboard box. It needs to be big enough to tape a CD or DVD on the inner edge. Small shipping boxes, cereal boxes, or shoe boxes will work.
    • A DVD or CD. The DVD or CD will get taped down, so pick one that you don’t mind losing.
    • 2 business cards (or a 3x5 cards). Make sure the card is thicker than standard paper. Some people substitute this for two single edged razor blades, but business cards are less dangerous to handle.[2]
    • A cardboard tube. A toilet paper, paper towel, or gift wrap tube will work.
    • Aluminum tape or aluminum foil and glue.
    • Scissors.
    • Pen or marker
    • Ruler
    • Cellophane tape
  2. Outline the viewing port. For now, leave the top of the box open as you make the spectrum. This port needs to be drawn on the outside of the box. First, set the CD or DVD on one side of the box, half of an inch away from the left edge. Use your pen or marker to trace the circle in the middle of the disc. Put the disk aside for now. Then, get your paper tube, and center it over the circle you traced. Trace the inner part of the paper tube.
    • Now, move the tube over half an inch, and trace the inner part of it again.
    • These circles will tell you where to cut the box to make the viewing port.
    • The two overlapping circles will look like an oval.
  3. Use scissors to cut the oval out of the box. Cardboard boxes can be hard to cut, so be careful with the scissors. You can also use a knife if the scissors are not working. The oval cutout will allow the paper tube to enter the box at an angle to make the viewing port.
  4. Cut a rectangle for the viewing slit.[3] Turn the box so the oval you cut is on the right-hand side instead of facing you. Place the disk towards the left edge of this side of the box. Use your pen or marker to trace the circle in the middle of the disc. This circle will be your guide for cutting out the viewing slit, which will be about half inch wide and two inches high.
    • Cut a small rectangle out of the box at the height marked by the small circle you made with the disk.
    • This slit will not be in a circular shape, but you want to use the height of the circle as a guide for cutting the rectangle.
    • Now, the right-hand side of the box should have an oval cutout, and the left-hand side should have a small rectangle cutout.
  5. Tape two business cards parallel to each other over the rectangle cutout. First, set the cards parallel over the rectangle, but leave a small gap between them. It should be a couple of centimeters. Make sure the gap is not be wider at the top or bottom. This will make a very small slit through which light enters the spectrum.
    • If you decide to use razor blades, set them up in the same way, but be careful handling the sharp edges.
    • Tape down the business cards. Now, you have made the viewing slit.
  6. Tape the disk to the inner side of the box opposite the viewing slit. Tape the disk inside the box so the colorful side is facing the viewing slit. The left edge of the disk should be the same distance from the left of the box as the slit is. Secure the disk in place with tape.
  7. Seal the sides of the box using aluminum foil and glue. Leave the top open for now. Doing one edge at a time, glue aluminum foil to the outside of the entire box, or cover it with aluminum tape. Cover any region where light might get in, but leave the section surrounding the viewing port and viewing slit uncovered.
  8. Insert the paper tube into the oval. Place the paper tube you have inside the oval you cutout earlier. Allow half an inch of the tube to go inside the box. Angle the interior end toward the disk. The paper tube should fit snugly inside the oval.
  9. Tape the tube in place. Tape the tube in place so it isn’t loose, but make sure it is still facing the disc after you tape it.
  10. Check to see if the spectrum works. Gently close the top of the box, but do not tape it shut yet. Look through the paper tube to make sure it is facing the disk. Adjust accordingly.
  11. Use aluminum foil and glue to seal up the edges. Now, you can close the box. Seal up any edges by gluing aluminum foil over them. The aluminum foil will make a tight seal around the edges to prevent light from coming in. Once you have sealed up the edges, allow the glue to completely dry. Now, you are ready to use your spectrum.

Making Observations with the Spectrum

  1. Examine different light sources.[4] Hold the spectrum up to a light, putting the viewing port (the paper tube) over your eye and aiming the viewing slit at a light. You should see the full light spectrum, from red to purple. Look at a candle flame, a flashlight, a street light, and so on by aiming the viewing slit at different lights.
    • If you are having difficulty seeing the light spectrum, try adjusting the paper tube. Remember, it must be facing the disk inside the box.
    • Use caution when examining sunlight: never look directly at the sun through the spectrum.[1]
    • If you want to observe the sun, look at the sunlight bouncing off of a white wall.
  2. Record your observations. Record how different light sources look in the spectrum by writing down the light source (such as “candle flame”) then using colored pencils to draw the colors you see.
    • An incandescent light bulb produces a continuous spectrum of light with no bright lines because of the tungsten in it.
    • A fluorescent bulb produces distinct, colored lines that come from mercury vapor.
    • Hot gasses produce light that is made up of only a few colors, which the spectrum allows you to see individually.
  3. Ask scientific questions about the spectrum in class or with friends. Some examples are: what colors were the individual bands of light reflecting? Was there an order to the colors? If so, name the order. Did different light sources look differently? How and why?
    • Look for specific colors. Are all the colors of the rainbow present?
    • Observe the spacing between the colored lines. Are they close or far apart?
  4. Enter your spectrum and observations in a science fair. Spectrums make great science fair projects. Ask an adult for help finding out more information about your local science fair or other similar competition.

Warnings

  • Never look at the sun through your spectrum. This will damage your eyes.

Tips

  • A good science project using your home-made spectroscope is testing different light sources and seeing the different light spectrums they produce.

Things You'll Need

  • A cardboard box
  • A DVD or CD you don’t mind losing
  • 1-2 business cards (or a 3x5 card)
  • A cardboard tube
  • Aluminum tape or aluminum foil and glue
  • Scissors
  • Pen or marker
  • Ruler
  • Cellophane tape

Related Articles

Sources and Citations

  1. ↑ 1.0 1.1 http://coolcosmos.ipac.caltech.edu/cosmic_games/spectra/makeGrating.htm
  2. ↑ http://sci-toys.com/scitoys/scitoys/light/cd_spectroscope/spectroscope.html
  3. ↑ https://www.cs.cmu.edu/~zhuxj/astro/html/spectrometer.html
  4. ↑ http://www.scienceinschool.org/2007/issue4/spectrometer
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