Northwestern Physics Demos                                 Go back to Sound
  
DCS# 3B30.30NWU# S-13Location:    7 B 6
title: Bell in a Vacuum 


Description:
A bell hangs suspended in a bell jar.  When the power supply is turned on, the bell sounds and can be heard by the class.  When the vacuum pump is activated, and the pressure drops sufficiently, the bell cannot be heard and the small balloon inside inflates.
   A valve attached to the vacuum line will bleed air back into the jar.

Questions:
    What happens if the vacuum is less than perfect?
   
pix of set upcloseup