DIY spectroscope

Explore the composition of light!

15 minutes


  • Carefully review the general safety advice on the back of the box cover before starting the experiment.
  • Disassemble the setup after the experiment.


  • Dispose of solid waste together with household garbage.

Scientific description

Let’s recall that rays of light come in different colors. If several rays of different colors combine, they mix to form a ray with a new color. A mixed beam can be divided into its components; scientists call the product of this separation a spectrum. A rainbow is the separation of white light into its component rays, that is, its spectrum.

With the help of a special device that divides a light beam into its components—a spectroscope—you have created your own rainbow. Let's see how it works. White light enters the spectroscope through a small slit, then passes into the hole where a special plate is glued—a diffraction grating. It changes the direction of rays of different colors in different ways, thus dividing the white beam into its colored components.

When you place a filter in front of the slit through which light enters the spectroscope, some colors disappear from the spectrum. The color of the filter itself also depends on which rays it transmits. If the filter absorbs blue, then we see it as yellow, because a mixture of colored rays from the white light spectrum without a blue ray creates a yellow ray. Take your spectroscope for a walk and use it to examine a variety of light sources such as streetlights, display lights, and more. Now test your device indoors: check out the light from your desk lamp, wall light, phone, and TV screen. Is there any difference?