3B30.30 Buzzer in a Bell Jar
Air as the medium for sound waves
A buzzer goes from loud to almost inaudible when placed in a vacuum chamber which has its air pumped out.
-  Pump
-  Bell jar
-  Buzzer
-  Hook
-  Duct tape
-  Power bar
-  Extension cord
- Tape the hook to the top of the bell jar.
- Position the bell jar where students can see it.
- Place the pump nearby, plugged into a power bar for an on-off switch.
- Arrange the buzzer's strap for easy hanging on the hook.
- Twist the buzzer wires together once to activate.
- Hang the buzzer inside the bell jar.
- Connect the hose from the pump to the bell jar.
- Activate the pump. The buzzer should become nearly inaudible, even from up close.
- Turn off the pump.
- Disconnect the hose to let air back in. The buzzer should become highly audible again.
- Separate the buzzer wires.
- PIRA 3B30.30
- Don't attempt this at home!
If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.