 |
| Graphical Representation of Waves |
|
| Whenever a wave passes through a medium, there is a change in some property of the medium. Hence, the waves can be graphically represented by showing the changes in the value of any such property of the medium as the waves travel through it. |
| |
|
| The longitudinal waves travel in the form of compressions and rarefactions and always compression follow a rarefaction or vice versa. Whenever there is compression the density of particles of the medium is higher than the normal density, while in a rarefaction, the density of the particles is lower than the normal density. The figure below gives the distance-density graph for a longitudinal wave. |
| |
 |
| |
| Distance-density graph for a longitudinal wave |
| |
| In the above graph, the horizontal dotted line represents the normal density of the medium. All the points above the dotted line represents higher densities and the points below the dotted line represents lower densities than the normal density. |
| |
| The particle density at any particular point on a longitudinal wave alternatively increases and decreases also with time at regular intervals as shown in the figure. |
| |
 |
| |
| Particle density in a longitudinal wave |
| |
|
| |
| Transverse waves propagate in the form of crests and troughs, i.e., some particles get displaced upwards, while some others downwards from their mean positions. Therefore, a transverse wave can be described graphically by a displacement-distance graph as shown below. |
| |
 |
| |
| Displacement-distance graph |
| |
| A transverse wave dampens after travelling some distance i.e. with time. Therefore, the displacement-time graph for a transverse wave is as shown in the figure. |
| |
 |
| |
| Displacement-time graph |
| |
