You will need:
- Candle
- Matchbox
- Metal sieve (large chalni) or metal gauze
Do you know the flame produced by a candle
is hollow? Find out how and why through this
experiment.
INSTRUCTIONS
- Ask an adult to help you light a candle. Wait for the flame to grow a bit in height.
- Once the flame is large, gently ask the adult to place a metal sieve or piece of metal gauze just over the flame.
- Look at the flame from the top,
through the metal sieve. How does
the flame look? - Now, look at the flame from the side, and ask the adult to move the metal sieve lower onto the top of the flame? Keep moving the sieve further downwards, till it is at the bottom of the flame.
- What do you notice?
RESULT
When the metal sieve is place on top of the flame, from the top you will notice that the flame is actually hollow. This is because of the process in which the wax from the candle is used as fuel for burning the flame. The wax gets heated up and is drawn upwards into the flame, due to surface tension. As soon as it is in contact with the flame, it also comes into contact with oxygen because of which it produces carbon dioxide and water vapour. But since this reaction takes place only on the outer surface of the flame where the wax meets the air, the inside is hollow. Also, because of the metal sieve the reaction cools down and stops the wax from completely burning, resulting in soot particles mixing with the wax particles and oxygen. When the sieve is brought further down, it does not give the wax a lot of time to react with the oxygen, resulting in un-burnt wax particles mixing with smoke, making it white.
