A "mechanical" wave is a disturbance in a medium which moves through the medium thus transferring energy from one place to another.

Examples

waves on the surface of a liquid,

sound waves,

waves on stretched wires/strings/springs.

Electro-magnetic radiations, for example light, x-rays, radio waves etc behave, in many situations like waves.

However, they differ from other waves in that they can travel through empty space.

The medium through which the wave is moving is the spring. The direction of motion of the wave (direction of propagation) is at 90° to the direction of the disturbance (or displacement) of the medium.

In these waves, the direction of the disturbance of the medium is parallel to the direction of propagation. Sound waves are longitudinal waves.

The velocity of propagation of a wave depends on the properties of the medium through which it moves.

• Waves Chapters Index
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