Waves are caused by vibration in a medium which carries energy from one point to another without a direct contact between the two points.
Machenical waves are also known as elastic waves. These waves need a material medium for their propagation(travel). Sound waves and water waves are example of mechanical waves.
These waves do not need a material medium to propogate(travel). They can travel even through vaccum, they travelles with a very high speed of 3 × 108 m/s.
A wave in which the particles of the medium vibrate up and down(at right angles) to the direcction in which the wave is moving, is called a transverse wave. The water waves formed on the surgace of water in a pond are example of transverse wave.
A wave in which the particles of the medium vibrates back and forth in the 'same direction' in which the wave is moving is called a longitudinal wave. The wave travelling along a spring when it is pushed and pulled are longitudinal waves.
A waves set up by a single disturbance in the medium are called pulses. The formation of water waves on the surface of water when a stone is dropped into it is an example of wave pulses, the sound waves produced by te clapping og hands is also an example of wave pulss
The waves which are caused by continuous disturbance in the medium occurring due to regular vibrations are valled periodic waves. Periodic waves are repeative in nature. When a periodic wave is formed, the medium oscillates for a long time after it is disturbed.
Characterstics of Waves
To understand the concept of waves we must know the characterstics of waves. The main characterstics of waves are as follow:
- Wavelength: The distance between two nearest points in a wave which are in the same phase of vibration is known as the wavelength.
- Amplitude: The maximum height or distance moved by a point on a vibrating body or wave, measured from its equilibrium(central) position.
- Time Period: The time required to produce one complete wave is called time period of the wave.The time taken to cimplete one vibration is called time period.
- Frequency: The number of vibrations produced in one second is called frequency of the wave
- Velocity of wave: The distance travelled by a wave in one second is called velocity of the wave. Velocity of wave = Frequency of wave × wavelength of wave