How sound waves work and why nothing can be heard in a vacuum. Sound is created through vibration. This is illustrated with reference to a hand bell, a humming bird and buzzing insects. Sounds cannot be heard in a vacuum, as waves need air to carry them. Sounds can travel through some materials, but a closed door will reduce noise, as the sound is reflected.
- This clip is from:
- First broadcast:
- 22 April 2008
Could be used to stimulate practical work and test some other sounds. How are they made, made louder, reduced or muted by the introduction of other materials, such as closing a door, covering your ears or enclosing the sound?