Description :
A classic demonstration of the fact that sound requires a medium to travel. It consists of an electric bell mounted in an acrylic jar. The jar is open at lower end and has a hole at the top, which accepts a rubber stopper with two holes. The stopper is fitted with two nickel plated brass rods, which act as terminals and also supports the bell within the jar. Supplied complete with rubber stopper, terminals and bell but supplied without pump plate.