Dispersion in a Prism

In this simulation, white light passing through air enters one face of an equilateral prism, and is dispersed into its various colors. Six rays of different colors are shown as they pass through and, eventually, exit the prism. Which colors deflect the most as they pass through the prism? Which deflect the least? Why? (You may drag the source of incident light along the left edge of the illustration and watch the effect on the dispersion of rays.)


  1. Snell's law governs the refraction of light at each boundary between air and glass.
  2. How does the index of refraction of the glass depend upon the frequency of the light wave?
  3. Which colors of light have higher (lower) frequencies?
  4. Which colors have higher (lower) indices of refraction?
  5. Which should be bent more (less) at each air-glass boundary?


See Serway and Beichner, Physics For Scientists and Engineers 5th Edition, Section 35.7

Illustration written by Chuck Niederriter and Steve Mellema