Ringing bell in vacuum


To illustrate some basic properties of sound waves; namely, that they don’t propagate in a vacuum.



  • Glass vacuum cover with bell assembly(shelf D4 or D1)
  • Vacuum pump base plate (shelf D1)
  • Vacuum pump (between shelves C and D)
  • Power source?  (shelf ?)

Set up

Place vacuum cover with bell assembly on vacuum base plate and connect vacuum pump to base plate. Connect bell leads to power source. Start the vacuum pump and notice that the ringing of the bell gets quiter as more air gets pumped out.