Make a Spectrum

by littleBits

Published on April 24, 2014

Explore light waves you can see with a bright LED and a CD.

A spectrum is a range of electromagnetic waves in order of their wavelength. You can always remember the order by thinking of "ROY G BIV". From longest to shortest-Red, Orange, Yellow, Green, Blue, Indigo, Violet. 

As white light bends, each color in the spectrum bends at a slightly different angle because their wavelengths are different sizes. Shorter wavelengths will bend more and longer wavelengths will bend less. 

Why does a CD behave like a prism? They both act as "diffraction grating." The grooves on a CD diffract light into several beams like you saw in this experiment!

You can also find this project on page 15 in the Space Kit booklet.

How To Make It


Make the circuit in the image gallery.


Find a dark place and set the reflective side of the CD opposite a white wall or piece of paper.


Place a bright LED in between the CD and the wall (or paper).


Make a spectrum! How many colors can you find?

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