Question

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

Answer 1

Hint: Generally we will use the bell jar experiment to identify the sound needs a material medium for its propagation
Usually, the sound waves cannot pass through the vacuum.
The medium may be a solid, gas, or liquid.

Complete answer:
The sound can travel in the mechanical wave. A mechanical wave is a kind of disturbance that can transport energy from one point to another point through the medium.
The vibrating object makes a disturbance in the sound. The medium can be any series of interconnected particles which implies the sound can travel through the medium.
If we consider the air as a medium the sound waves are propagated like longitudinal waves with compressions and rarefactions. The vacuum does not have any molecules that can vibrate and carry the sound waves so the sound waves cannot travel through the vacuum. To prove this statement we have an experiment which is known as the bell jar experiment.
The apparatus required for the bell jar experiment is as follows,
- A strong jar
- Electronic bell.
- Cork
- Vacuum pump.
Pick an electronic bell then connect it to the electrical supply. Check whether the bell is a ring or not. Then connect the strong jar and electric bell to the vacuum pump.
Suspend the bell inside the jar and switch on the bell. We can hear the bell sound now pumping out the air from the jar and we can not hear any sound from the jar because we pumped out all the air from the jar. From this experiment, we can understand that sound needs a medium to travel.


Note: The audible frequency range is $20Hz$ to $20KHz$
The frequency below $20Hz$ is called the infrasonic.
The frequency above $20KHz$ is called the ultrasonic.