Watch as water is sucked up into an overturned glass.
What you’ll need:
- shallow dish
- candle
- blu-tack
- water
- food dye (to colour water to make it easier to see, optional)
- matches
- tall glass
What to do:
- Add a few drops of food dye to some water so you can see the water easily (optional).
- Using blu-tack, stick a candle to the bottom of a shallow dish.
- Pour the water into the dish so it surrounds the candle.
- Light the candle.
- Turn the glass over and place it over the top of the candle.
What happens:
The candle will burn for a few seconds before going out – it goes out because all the oxygen is used up and fire needs oxygen to burn. As the candle goes out, water will enter the glass. Depending on the width of the glass, the water may go above the top of the candle (for very narrow glasses). As the candle burns, the air inside the glass heats up and expands. When the candle goes out, the air cools down and contracts, taking up less space inside the glass. This causes water to be pushed into the glass to fill the space and equalise the pressure on the inside of the glass.