A wave is a vibratory disturbance in a medium which carries energy from one point to another point without any actual movement of the medium. There are three types of waves
- Mechanical Waves Those waves which require a material medium for their propagation, are called mechanical waves, e.g., sound waves, water waves etc.
- Electromagnetic Waves Those waves which do not require a material medium for their propagation, are called electromagnetic waves, e.g., light waves, radio waves etc.
- Matter Waves These waves are commonly used in modern technology but they are unfamiliar to us. Thses waves are associated with electrons, protons and other fundamental particles.
Nature of Waves
(i) Transverse waves A wave in which the particles of the medium vibrate at right angles to the direction of propagation of wave, is called a transverse wave.
These waves travel in the form of crests and troughs.
(ii) Longitudinal waves A wave in which the particles of the medium vibrate in the same direction in which wave is propagating, is called a longitudinal wave.
These waves travel in the form of compressions and rarefactions.
Some Important Terms of Wave Motion
- (i) Wavelength The distance between two nearest points in a wave which are in the same phase of vibration is called the wavelength (λ).
- (ii) Time Period Time taken to complete one vibration is called time period (T).
- (iii) Frequency The number of vibrations completed in one second is called frequency of the wave.
Its SI unit is hertz.
- (iv) Velocity of Wave or Wave Velocity The distance travelled by a wave in one second is called velocity of the wave (u).
Relation among velocity, frequency and wavelength of a wave is given by v = fλ.
- (v) Particle Velocity The velocity of the particles executing SHM is called particle velocity.