Invisible glass

Invisible glass

This experiment has a cool effect, with the glass rod appearing to disappear.

Ingredients and equipment that you will need

A glass of water
A glass of babyoil or glycerine (both are easily available at the chemists)
A glass rod or a test-tube

Method and further information

Put the glass rod or test-tube into the water and you can still see it easily. Put it into babyoil or glycerine and it disappears completely

Light travels through water and glass and babyoil, which is why they look transparent. But the light is bent as it goes through and we can detect that bending.

Light is bent differently in water compared to glass so we see the difference and see the glass. The bending is the same in babyoil as in glass, so we can’t see the glass.

Be careful – you should ask an adult to help you with these experiments. Do your experiments in old yoghurt pots, jam jars or bottle tops. Don’t use cups or glasses in case someone thinks it’s a drink.