Egg In A Bottle
This classic science demonstration never ceases to amaze. Get a hard-boiled egg through a small bottle neck opening and into the bottle without touching it. A great way to learn about air pressure.
Suitable for kids aged 10+ with parental supervisionCAUTION
This experiment requires the use of matches and a small flame. Please exercise caution, and only perform under adult supervision.
- A hard-boiled egg with the shell removed
- A glass bottle with a mouth slightly smaller than the egg (fruit-drink bottles work well)
- Small piece of newspaper about 10cm square
What to do:
- Place the shelled egg on the mouth of the bottle to prove that the egg does not fit through the opening.
- Fold the newspaper into a strip so that it can be easily dropped into the bottle.
- Use the matches to ignite the folded strip of newspaper and remove the egg from the mouth of the bottle. Quickly drop the burning newspaper into the bottle.
- Watch what happens. Within a few minutes the egg should squeeze through the opening and into the bottle. Why?
- If the egg is more than about a centimetre bigger than the opening of the bottle it may break upon entering. To prevent this use a smaller egg, or rub some oil around the mouth of the bottle. A water-filled balloon can be used in place of the egg.
Why is it so?
A change in air pressure causes the egg to be pushed into the bottle. The air pressure inside and outside the bottle is the same at the beginning of the experiment. When the burning paper is dropped into the bottle, the air inside heats-up and expands. After the burning newspaper goes out, the air cools and contracts. The air inside the bottle has a lower pressure than the air outside, and the high pressure air outside pushes the egg into the bottle.