Piezo Buzzer in Vacuum Chamber

The sound of the buzzer at decreases as the chamber is evacuated, but it never is extinguished. The obvious difference comes when the air is let back into the chamber. It does demonstrate the concept; it just isn't a "WOW" demonstration.

Serviceable

This is a good demonstration. If you can, get the electric pump. It is difficult to pump out enough air with the hand pump.