Part of the show Stem Cells, Brain Repair and Tricks of the Light
What you Need
What to do
Poar the vegetable oil into the large container
Look for the bowl under the oil.
What may happen
The part of the pyrex bowl that is completely under the oil seems to disappear, you can't see it any more!
Why does it happen?
The first question to ask is why can we see the transparent bowl in the first place - it is see through so how can we see it?
However light goes at the same speed in vegetable oil as in the pyrex. This means that the light isn't reflected or refracted when it passes from the oil to the pyrex, so you have no way of seeing the bowl.
Why does changing the speed of light cause distortions?
Imagine a formation of soldiers marching fast on tarmac, then veering off into some sand which they can't march nearly as fast on.
Because the soldiers on the sand are marching more slowly, they are closer together. The only way they can maintain their formation stay next to their neigbour is to change direction.
When the soldiers leave the sand the first ones to get off it will speed up so the process hapens in reverse.
Light is a wave, and wavefronts (the line long the top of a wave), behave in much the same way as our soldiers. So if light enters a substance it travels more slowly in, it will change direction.