Make Your Own Rainbow

Prism rainbow

What you'll need:
  • A glass of water (about three quarters full)
  • White paper
  • A sunny day

  1. Take the glass of water and paper to a part of the room with sunlight (near a window is good).
  2. Hold the glass of water (being careful not to spill it) above the paper and watch as sunlight passes through the glass of water, refracts (bends) and forms a rainbow of colors on your sheet of paper.
  3. Try holding the glass of water at different heights and angles to see if it has a different effect.
What's happening?
While you normally see a rainbow as an arc of color in the sky, they can also form in other situations. You may have seen a rainbow in a water fountain or in the mist of a waterfall and you can even make your own such as you did in this experiment.
Rainbows form in the sky when sunlight refracts (bends) as it passes through raindrops, it acts in the same way when it passes through your glass of water. The sunlight refracts, separating it into the colors red, orange, yellow, green, blue, indigo and violet.