Sound Requires a Medium for Propagation(Sound Can't Travel through Vacuum) Video Lecture - Class 8

Topic: Sound.
Why can't we hear sound in space?
Do you know what sound is and how we are able to hear it?
Sound is a form of energy which creates a
sensation of hearing.
It always needs a medium to travel.
In this case, air is the medium.
When we play songs, the diaphragms of the loudspeakers vibrate.
This makes the adjacent air molecules vibrate.
These vibrating air molecules pass on the
vibrations to the nearby air molecules.
In this way, the vibrations travel from one
point to another.
Eventually, when these vibrations reach our ears, they create a sensation of hearing.
Hey.
Did you see that?
He was able to hear sound through a solid metal box?
How is that even possible?
It is possible because sound can travel through solids also.
We know that sound needs a medium to travel.
That medium can either be a solid, liquid
or gas.
Sound travels with the help of molecules present in the medium.
However, as compared to liquids and gases, the molecules of solids are very closely packed together.
Hence, when molecules of a solid vibrate.
They pass on the vibrations to the surrounding molecules more effectively.
Thus, we can conclude that sound travels more effectively through solids.
As compared to liquids and gases.
So, why wasn't he able to hear the sound?
This is because when the air is completely removed.
An empty space devoid of any air, that is, a vacuum is created.
Vacuum does not have any kind of medium.
That means it does not have any molecules.
As there are no molecules that can vibrate and transmit sound, vibrations cannot reach his ears.
Thus, he does not get a sensation of hearing.
Similar phenomenon takes place in space as well.
Space is also a vacuum.
It does not have any medium.
Thus, we can't hear sound in space.