oil & glass refraction

Watch the test tubes disappear!

How it works

Light travels at different speeds through different substances. This change in speeds causes light to refract (bend). When two substances have the same index of refraction, light passes through it at the exact same speed and our eyes cannot tell the difference between them.

diagram showing the difference in indices of refraction in oil, glass, and water

Try this at home 

  • Try putting a pencil or a spoon in a glass of water, and look at it from different angles. Do you see refraction occurring?

  • What happens when you put the pencil in different liquids? Do they all have the same index of refraction?


  • Physics: the study of forces, matter, motion, and energy

  • Refraction: when light bends or changes direction when it passes through substances of different densities

  • Index of Refraction: describes how light travels through different substances/mediums

What's going on in Waterloo

At the Perimeter Institute for Theoretical Physics, scientists are looking for answers about our universe; from the very largest to the very smallest. Sometimes the simplest questions lead us to the most profound insights! 

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How to become a physicist

The first step to becoming a physics student is to graduate from high school with the required math, science, and english courses. After high school, you will attend a post-secondary program. Physics students at Waterloo explore, investigate, and discover the natural laws and processes of non-living matter.