Wave

A wave is a disturbance which propagates energy from one place to the other without the transport of matter.

Waves are broadly of two types

(i)                  Mechanical Wave   (ii)  Non-mechanical wave

Mechanical Wave: The waves which require material medium (solid, liquid or gas) for their propagation are called mechanical waves or elastic wave.

Mechanical wave are of two types

(i)                  Longitudinal wave:  If the particles of the medium vibrate perpendicular to the direction of propagation of wave, the wave is called longitudinal wave.

Waves on springs or sound waves in air are examples of longitudinal waves.

(ii)                Transverse wave: If the particles of the medium vibrate perpendicular to the direction of propagation of wave, the wave is called transverse wave.

Waves on strings under tension, waves on the surface of water are examples of transverse waves.  

Non-mechanical waves of electromagnetic waves: The waves which do not require medium for their propagation i.e. which can propagate even through the vacuum are called non mechanical wave.

Light, heats are the example of non-mechanical wave. In fact all the electromagnetic waves are non-mechanical.

All the electromagnetic wave consists of photon.

The wavelength range of electromagnetic wave is 10⁻¹⁴ m to 10⁴ m.