Describe with the help of a diagram, how compressions and rarefactions are produced in air near a source of sound.

Explanation

(i) When the particles of the vibrating object moves forward during vibration, it pushes the air in front of it and compresses the air creating a region of high pressure called compression (C).
(ii) After that they start moving away from the surface of the vibrating object in backward direction.
(iii) As this occurs the surface moves backward creating a region of low pressure called rarefaction (R). This is followed by formation of a chain of compression and rare faction.