Sound is produced by a vibrating body.A material medium is necessary for the propagation of sound waves .In wave motion momentum and energy are transferred.Charactrestics of wave motion
1. Wave motion is a disturbance produced in the medium by the repeated periodic motion of the particles of the medium.
2. Only the wave travels forward whereas the particles of the medium vibrate about their mean position.
3. there is regular phase change between various particles of the medium. The particle ahead starts a vibrating a little later than the particles preceding it.
4. the velocity of the wave is different from the velocity with which the particles of the medium are vibrating about their mean position. The wave travels with a uniform velocity whereas the velocity of the particle is different at different positions. It is maximum at the mean position and zero at the extreme positions of the particles. There are two types of wave motions
a. Transverse wave
b. Longitudinal Wave
Sound waves are longitudinal waves and light waves are transverse waves. Figure 1 shows the formation and propagation of transverse and longitudinal wave.
A sound wave is propagated and conveyed to the ear by means of the intervening layers of air. Consider a vibrating tuning fork as shown in figure 2. Let us confine our attention to the right hand prong only. When it moves towards the right, it compresses the layer of air in front of it and as a consequence the pressure of this layer will be greater than the adjacent layers. It tends to relieve the strain thus created , by compressing them. These in turn hand on the compression. Thus a pluse of compression will travel onwards to the right. Again when the prong moves towards the left rarefraction are sent out in regular succession. These waves at last reach the ear and set the tympanic membrane, which is ultimately transmitted via a system of bones and cords to the brain and causes the mental sensation called sound
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