Question

cite an experiment to show that sound needs a material medium for its propagation.

Answer 1

Take an electric ringer and a water/air proof bell - jar container. The electric ringer is suspended inside a water/air proof container which is associated with a vacuum pump.  

Working :

1. When we press the switch, we will have the capacity to hear the ringer.  

2. When the air in the container is siphoned out progressively, the sound winds up weak despite the fact that a similar measure of current is moving through the ringer.

3. When the air is evacuated totally, we won't have the capacity to hear the sound of the ringer.  

Result :  

This test demonstrates that sound requires a proper medium for its propagation.

Answer 2

Connect glass-bell-jar with the vacuum-pump and suspend an electric-bell in it.

Connect the bell with a battery and switch on the electric bell & hear the sound of the bell.  

Remove the air with the help of vacuum pump from the jar and again hear the sound.

Now, the sound won’t come out because there was no air in the jar.