How to Make Glass Water Prisms

Updated April 17, 2017

A prism is a transparent object that separates light into individual beams. When light passes through a prism, it forms a rainbow. This is because the prism breaks white light and refracts it separately to form the colours of the rainbow. Make a simple prism with a glass of water and simple household materials.

Fill a clear glass with water, about halfway.

Place the half-filled water glass on an elevated surface, such as a window sill or a coffee table, so half the glass sits on the surface and the other half overlaps the edge of the surface. Be careful when positioning the glass, so it does not tip over and break.

Put a sheet of paper on the floor under where the glass sits on the elevated surface.

Turn on your flashlight and shine the light through the glass, angling down to the paper on the floor. If you do not see a rainbow, adjust the light's angle.

Things You'll Need

  • Glass
  • Water
  • Elevated area (coffee table, window sill)
  • Paper
  • Flashlight
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About the Author

Vivian Gomez contributes to Retailing Today, the Daily Puppy, Paw Nation and other websites. She's covered the New York Comic Con for NonProductive since 2009 and writes about everything from responsible pet ownership to comic books to the manner in which smart phones are changing the way people shop. Gomez received her Bachelor of Arts in English literature from Pace University.