Bell In Vacuum

Demonstrates That Sound Waves Need Material Medium For Propagation And Cannot Travel Through Vacuum. For Use On Pump Plates With Diameter At Least 15Cm. It Consists Of An Electric Bell Operating On 4V- 6V Ac/Dc, Suspended Inside Glass Bell Jar Through A Pair Of Thick Metal Wires From A Rubber Bung That Seals The Jar From The Top. 4Mm Termils Provided For Electrical Connections To The Bell. Sizes (Height x Diameter) Of Bell Jars Available Are: (8” x 4”)