Refractive Index
Light, Sound and Waves

Invisible Bowl

Enrichment Activity for 5-11 11-14

What you need

  • A large Pyrex® bowl
  • A small Pyrex® bowl
  • Vegetable oil


  1. Pour enough vegetable oil into the large Pyrex® bowl so you’ll be able to completely submerge the small bowl in it
  2. Carefully lower the small bowl into the vegetable oil
  3. The small bowl disappears as it gets covered in oil!

Results and Explanation

The refractive index of Pyrex® glass is the same as that for vegetable oil so as light passes through the glass of both bowls and the oil it doesn’t bend – refract – at all and you can’t see the small bowl.

These experiments have not been specifically safety tested for home use but we believe them to be safe if the instructions are followed. Adult supervision or direction is recommended as appropriate. All experiments are carried out at your own risk.

Refractive Index
appears in the relation n_1/n_2=sin(θ_2)/sin(θ_1) n=v/c
is used in analyses relating to Refraction
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