Homemade Spectrometer

Homemade Spectrometer

Turns out theres a lot more to white light than meets the eye. Here's a simple spectrometer you can build yourself, using just a spare CD, an empty cereal box and a pair of scissors.

Suitable for kids aged 11 +
You Need:
  • Cereal box
  • Compact Disk
  • Utility knife/Scissor
  • Protractor


What to do:
  1. Cut a 1" slit on the side of the cereal box just below the nutrition information.
  2. Cut a slit across the opposite side of the box and extend it 1" on either side at an angle 45 degrees above the horizontal. Use a protractor to measure the exact angle.
  3. Slide a CD into this slit.
  4. Make an eye hole on the bottom of the box below the CD.
  5. Point your spectrometer at a bright light source and look through the eye hole!


Why is it so?

Light can be split into its spectrum of colours using a spectrometer. Different light sources will give different spectra through the spectrometer. Different spectra or "rainbows" are displayed from different light sources because they are made up of different elements.

For example a street light will have a different spectra to a laptop screen, as old street lamps are primarily made up of the element sodium, which gives off a strong yellow colour, as can be seen when burning Sodium Chloride! How do scientists know which elements make up far away stars? They point their spectrometers at them and analyse their spectra, from the spectra and black lines that are observed, scientists are able to deduce what gases stars are composed of. The spectra of our sun shows that it is made of mainly hydrogen! WOW!