Wave Properties of Sound: Wave Motion

Bell in a Vacuum
PIRA Class: 3B30.30

Purpose
To demonstrate that sound waves require a medium for propagation.

Description
Start the bell for students to note the sound of the bell under the bell jar.
- Turn pump on, wait ~ 2 minutes to produce a good vacuum, during which the sound intensity will decrease
- Turn off vacuum pump and slowly let air back into bell jar, during which the sound intensity will increase

Equipment
Bell jar & doorbell
Support Equipment
Vacuum pump