Download PDF – Speed of sound in different media

As we know that, the sound of thunder is heard a little later than the flash of light is seen. Thus, it is true that the speed of sound is much less than the speed of light.

Speed of light = 3 × 10 ⁸ m/s

Speed of sound = 344 m/s

The sound cannot travel at the same speed in different mediums.

The speed of the sound in a medium is affected by the following things :

1.  It depends upon the density of the medium. For instance – The speed of sound is maximum through solid.

2.  It depends upon the temperature of the medium. For instance – As the temperature increases, so does the speed of sound.

3.  It also depends on the humidity in the air. For instance – As humidity increases, so does the propagation of sound.

Sonic Boom :

 When an object travels in the air with speed more than that of the sound, it results in sound with high energy.
This energy is loud enough that can break glasses or damage the buildings. The sound produced is a similarity to the sound of an explosion or thunderclap.

These objects exert a large amount of pressure on the air which causes the production of the shock waves in the air. These waves produce extremely large and loud sound waves which are known as Sonic Booms.

A good reflector of sound = The material through which sound can bounce off is known as Good reflector of sound.

For example – metals and walls ( metals or liquid ).
A bad reflector of sound = The material through which sound cannot bounce back is known as a bad reflector of sound.

For example – clothes, cotton or vacuum, etc.

Reflection of Sound :

 Like lights, sound can also get reflected or bounces off like a rubber ball, at the surface of solid or liquid and follows the same law of reflection.

This law states that the incident sound wave, the reflected sound wave and the normal, all the three lies in the same plane.

It can also be defined as the direction in which the sound is incident and is reflected make equal angles with the normal to the reflecting surface at the point of incidence.

Angle of incidence = angle of reflection
i.e., i = r

Echo :

When we hear the same sound of something again and again in any medium, it is known as Echo.

For example – If we shout or clap near a suitable reflecting object such a tall building or a mountain, we hear the same sound of clap again a little later.

The sensation of sound persists in our brain for about 0.1 seconds.

It is basically produced or formed due to the reflection of sound in any medium.

For hearing distance echoes, the minimum distance of the obstacle from the source of sound must be  17.2 m.

Successive of multiple reflections of a sound wave – The phenomenon of hearing echoes more than once.

For example – Roaring of thunder.