What you need:
A balloon
A friend to help you
What to do:
1. Blow up the balloon fully. Tie up its end.
2. Now, place the balloon next to your ear.
3. Ask your friend to tap the balloon lightly on the opposite side (that’s not against your head).
What happens:
Even though your friend is tapping lightly on the balloon, to your ear, it sounds pretty loud.
Why?
The balloon acts as a sound amplifier which means it makes the sound passing through it louder. When you blow up a balloon, you force air molecules to fit into a small space inside the balloon. Thus, the space between the molecules is also less in comparison to the air molecules floating around you, because they are pushed together. These closely-spaced molecules become better conductors of sound waves than normal air. And you get louder taps!
Picture Credit : Google
