# Longitudinal Wave Graphical Representation

In this post, we will study Longitudinal Wave Graphical representation. Here, we will see how the Density-Distance graph graphically represents a Longitudinal Wave.

When a Longitudinal Wave, say a sound wave passes through the air, the particles of air vibrate back and forth parallel to the direction of the sound wave. Thus, when a Longitudinal Wave travels in the horizontal direction, then the particles of the medium also vibrate back and forth in the horizontal direction.

When a longitudinal wave passes through a medium, say air, then some of the particles of air get crowded together and form compression, whereas other particles go farther apart and form a rarefaction.
So, a longitudinal wave is represented pictorially by showing the compressions and rarefactions.

Now, let’s see how a density-distance graph can represent the compression and rarefaction of a longitudinal wave.

## Density-Distance graph to graphically represent Longitudinal Wave

In a compression, the density of the medium, say air, is high whereas in a rarefaction, the density of the medium is low. Thus, when a longitudinal wave passes through the medium, then the density of the medium changes continuously.

So, a longitudinal wave in an air medium is represented graphically by plotting the density of air against the distance from the source. In other words, a longitudinal wave is represented by a density-distance graph (see figure 2).