A vibration that travels through the material world around us is known as sound. Before reaching our ears, these vibrations generate sound waves that travel across mediums like air and water.
Can sound travel in a vacuum? This question is explained below.
Can sound travel in a vacuum?
Sound cannot pass through an empty medium. Propagation of sound requires an elastic inert medium. This medium can be solid, liquid or gaseous. We hear sound because there is the air around us. This can be proved by the experiment below.
The Experiment to support that sound cannot travel in a vacuum
Bell Jar Experiment
A large glass Bell Jar was placed on the base of an air-extraction pump and the Bell Jar was air-tight by applying Vaseline to the contact between the base and the bell Jar. A rubber hood was placed over the opening of the Bell Jar and two metal wires were inserted through the hole and an electric bell was hung inside the Bell Jar with that wire. Outside the shell, the two ends of the wire are connected to a battery and key. When the key is pressed, the current will flow and the bell will continue to ring.
As the Bell Jar is full of air, a loud ringing sound can be heard from the outside. Now, by running the pump and taking out the air inside the Bell Jar gradually, the sound will become fainter and fainter. Once the Bell Jar is nearly empty of air, the sound will fade away. From outside, the hammer of the electric bell can be seen striking the bell but the sound is almost inaudible.
After that, if the air is slowly introduced into the bell jar, the sound of the bell will be heard gradually. When the Bell Jar is fully inflated, the sound will be just as loud as before. Experimenting with any other gas instead of air will give the same result. This experiment proved that sound cannot pass through a vacuum; the Propagation of sound requires an inert medium.