What you need:
A straw
A glass
Water
Scissors
What to do:
1. Using the scissors, cut through the straw partially so that a small portion of it stays attached when it is folded.
2. Bend the straw at a right angle at the point of the cut without breaking the straw.
3. Fill the glass three-quarters of the way with water.
4. Put the longer section of the straw into the water.
5. Now, holding the shorter section at 90 degrees, blow into the straw softly and continuously. Try pinching the top of the longer section to help.
What happens:
You hear a whistling sound.
Why?
The longer end of the straw is nothing but a column of air inside the water (it is filled with some water as well but mostly it is air). When you blow into the shorter section of the straw, your breath moves across the top of the longer straw. This causes the column of air in that part to vibrate. The vibrations travel through the air and reach your ears as the whistling sound you hear.
The pitch of the whistle depends on how much air there is in the longer section of the straw. So if you lower the straw into the water, or pull more of its length out of the glass, the sound you hear will change. Using this, you and your friends can come up with different tunes and form a whistling orchestra.
Picture Credit : Google
