 # In which of the following medium speed of the sound is maximum? (1) Steel (2) Wood (3) Water (4) Air (5) Helium

The speed of sound is the distance travelled per unit time by any sound.

## Definition

The speed of sound is defined as the dynamic propagation of sound waves. This depends on the characteristics of the medium through which the propagation takes place. Speed of sound is used for describing the speed of sound waves in an elastic medium.

## Speed of sound and density

When the medium is dense, the molecules in the medium are closely packed which means that the sound travels faster. Therefore, the speed of sound increases as the density of the medium increases.

### Solids

This means that the molecules are closer to each other in solids than in liquids and in liquids than in gases. This closeness due to density means that they can collide very quickly.

### Liquids

The density of a liquid is greater than the density of a gas. Therefore the distances between molecules are more in liquids than in solids but are less than in gases. Hence the speed of sound in liquids lies in between the speed of sound in solids and gases.

### Gases

Since gases expand to fill the given space, density is quite uniform irrespective of the type of gas.

From the above discussion we can conclude that

The velocity of the sound varies in the different medium as given below.

• Sound travels in solids at a rapid rate than air, fluid or vacuum.
• Through denser media, sound travels at a higher rate. The solid density is higher than the air, liquid and vacuum densities.
• The velocity of sound in Vacuum medium < Gas medium < Liquid medium < Solid medium.