Most everyone knows that an equilateral prism will refract white light into its constituent colors: a spectrum ranging from red to violet. But, if one uses two prisms, there’s much more to be discovered.
All that’s required:
– a source of white light
– a slit mounted on a large piece of cardboard
– two equilateral prisms
– two small pieces of card stock
– a square of ground glass.
The light source and slit are arranged as shown. A fairly narrow (1/4”) color spectrum will be displayed on the ground glass. Note that the light beams are DIVERGENT.