Wave motion is a mode of transmission of energy through a medium in the form of a disturbance. It is due to the repeated periodic motion of the particles of the medium about an equilibrium position transferring the energy from one particle to another.
The waves are of three types - mechanical, electromagnetic and matter waves. Mechanical waves can be produced only in media which possess elasticity and inertia. Water waves, sound waves and seismic waves are common examples of this type. Electromagnetic waves do not require any material medium for propagation. Radio waves, microwaves, infrared rays, visible light, the ultraviolet rays, X rays and γ rays are electromagnetic waves. The waves associated with particles like electrons, protons and fundamental particles in motion are matter waves.
Waves on surface of water
In order to understand the concept of wave motion, let us drop a stone in a trough of water. We find that small circular waves seem to originate from the point where the stone touches the surface of water. These waves spread out in all directions. It appears as if water moves away from that point. If a piece of paper is placed on the water surface, it will be observed that the piece of paper moves up and down, when the waves pass through it. This shows that the waves are formed due to the vibratory motion of the water particles, about their mean position.
Wave motion is a form of disturbance which travels through a medium due to the repeated periodic motion of the particles of the medium about their mean position. The motion is transferred continuously from one particle to its neighbouring particle.
Characteristics of wave motion
i. Wave motion is a form of disturbance travelling in the medium due to the periodic motion of the particles about their mean position.
ii. It is necessary that the medium should possess elasticity and inertia.
iii. All the particles of the medium do not receive the disturbance at the same instant (i.e) each particle begins to vibrate a little later than its predecessor.
iv. The wave velocity is different from the particle velocity. The velocity of a wave is constant for a given medium, whereas the velocity of the particles goes on changing and it becomes maximum in their mean position and zero in their extreme positions.
v. During the propagation of wave motion, there is transfer of energy from one particle to another without any actual transfer of the particles of the medium.
vi. The waves undergo reflection, refraction, diffraction and interference.