Material Required:

Hello Friends! I am Albert Einstein and Welcome to the Young Einstein Challenge where we will be exploring science beyond your books, around us in the things that surround us.

Today, we are going to do a magical science experiment to understand why and how hot air rises.

For this experiment, we need 6 things.

1. An A5 sheet of paper
2. A pencil/ marker to draw
3. Scissors
4. A candle
5. A matchbox
6. And A pin

Let the magic begin!

Conducting the Experiment:

1. Start with the A5 size sheet of paper. Use a marker to draw a swirl on it. Begin drawing at the centre and make continuous curves.
2. Use a scissor to cut out the swirl. It will look something like this.
   
3. Use a pin to punch a hole at the top of the paper swirl. Insert a thread through this hole and tie it up into a knot. This thread will help you hold the paper swirl in the air while balancing it. Notice how this paper swirl is not moving (yet).
4. Lighten up the candle using a matchstick.
5. Suspend the paper swirl in the air a few centimetres above the lit candle. And watch the paper swirl spin!

Scientific Principle and Application

Question: The Big Question is: What caused the paper swirl to spin?

SIMPLE! By lighting a candle, the air above the flame becomes hot. This hot air rises and makes the paper swirl spin.

But why does it even rise?

Air rises when we heat it because when we heat air, the tiny little air particles run away from each other and spread out. Anything that spreads out takes up more space and becomes less dense. Hot air is less dense than cold air and therefore it rises.

You many wonder why is hot air less dense than cold air when both of them are just the same substance – air?

The same substance can have different densities at different temperatures.

Hot air balloons go up because hot air rises. By heating the air inside the balloon with the burner, it becomes less dense than the cooler air on the outside. This causes the balloon to float upwards.

And yes, you guessed it right, it is the hot air inside the lantern that makes it rise up. So friends, remember hot air rises because it is less dense than cold air. And we can use this principle to make many interesting things like hot air balloons and lanterns

Let’s see if you can make some on your own.

To know more about density, do watch our next experiment – Rainbow in a Jar. So let the fun begin! Toodles!