To learn how vibrating air columns affect the pitch of sound
- • Six identical small-mouthed bottles or tall glasses
- • Metal spoon
- • Water
Pour different amounts of water in each glass or bottle. Line up the glasses from least to most full. Carefully tap each glass with the metal spoon. Do they sound alike?
The glass with the most water has the lowest pitch. The glass with the least amount of water has the highest pitch. Tapping the glasses causes the air to vibrate. When the air column is shorter, the air vibrates faster and the pitch is higher. As the height of the air column gets higher, the pitch of the sound gets lower.