Evanesco is a vanishing charm in the wizarding world. Professor McGonagall teaches it in The Order of the Phoenix where the students attempt to vanish snails and other small creatures.

In our activity, we will vanish glass objects in a beaker of oil based on their similar refractive indices. Refractive index is a measure of how light moves through a material – one of the things it tells us is how a light beam bends when it enters the material. If the refractive index of two materials is similar, the light won’t bend very much when it moves between them. Part of how we see glass objects relates to how the light refracts or bends when it moves through the object, and also how the light reflects off of the object. Here, we are using materials – glass and oil – that have very similar refractive properties. If we surround the glass objects with the oil, the light won’t change when it moves from the oil to the glass and we aren’t able to see the objects the way we usually would – making them appear to vanish. 

Here’s what to do:

  1. Collect supplies
    • Glass jar, beaker, or cup
    • Vegetable oil
    • Glass objects
  2. Place objects in the beaker
  3. Pour in the oil

Note: Not all glass has the same refractive index, so you will notice that some glass objects vanish better than others.

Watch here: