Bell and Vacuum Sound Jar Glass

Bell and Vacuum Demonstrator To demonstrate the principle that sound does not travel in vacuum. This is a modified unit which does not require external power source for the bell. Comes complete with Bell Jar, Bell which requires 2 AA batteries (not included), Vacuum Pump Plate and Vacuum Hose. Assembled unit is 8.5 in. x 11.5 in. Diameter x Height.