question_answer 19)

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

Answer:

(i) When a vibrating object moves forward, it pushes the air in front of it and compresses the air creating a region of high pressure called compression (C). (ii) It starts moving away from the surface of the vibrating object. (iii) As this occurs the surface moves backward creating a region of low pressure called rarefaction (R).