Home Demos > Physical Science
Next time someone has a birthday, try this experiment. Most people can blow out a cake-full of candles with a single blast of breath. Blowing out a single birthday candle should be even easier, shouldn’t it?
What You Need
- a plastic funnel
- a candle (it doesn’t have to be a birthday candle)
- an adult
Never use matches or candles without an adult around to keep an eye on things. A single match can start a fire that can destroy a whole building. But, it is just a match. So, just be careful.
What You Do
- Set the candle on a countertop.
- Have an adult light the candle.
- Place the narrow end of the funnel in your mouth.
- Holding the funnel so the wide end is about 20 centimeters (8 inches) from the candle flame.
- Now try the same experiment again, this time blowing into the wide end of the funnel, aiming the skinny end at the candle flame.
Blowing into the narrow end of the funnel forces your breath to spread out along the edges of the funnel walls. Hardly any air made it directly to the flame. But when you turn the funnel in the other direction, your breath takes an express train to candle flame, cooling it off and snuffing it out.