Wave is a phenomenon in nature where the energy is transferred from one point to another without moving the constituent particles. The important property of waves is that they transfer energy.
TYPES OF WAVES:
1. Mechanical wave:- The waves which require a material medium for their transmission are called mechanical wave/ elastic waves. In a mechanical wave, form of disturbance (energy) travels through a medium due to the repeated periodic motion of the particles of the medium about their mean position. Ex- sound wave, water wave, string wave etc.
2. Non- mechanical wave:- The waves which do not require a material medium for their transmission is called non-mechanical wave/ electromagnetic waves. They can travel through a vacuum also. Ex- all Electromagnetic waves.
The speed of sound waves in the air is about 340 m/s
The speed of Electromagnetic waves in a vacuum is
A third kind of wave is the so-called Matter-wave. They are associated with constituents of matter: electrons, protons, neutrons, atoms and molecules. They arise in the quantum mechanical description of nature.
Here we will study mechanical waves, which require a material medium for their propagation. Mechanical wave involves oscillation of constituent particles and depends on elastic properties of the medium.
NOTE
- A wave is not the motion of matter as a whole in a medium. The wind is different from the sound wave in the air. The wind involves the motion of air from one place to other. The sound involves compressions and rarefaction of layers of air.
- In a wave, energy and not matter is transferred from one point to another.
- Energy transfer takes place because of the coupling through elastic forces between neighbouring oscillating parts of the medium.