CBSE Class 12-science Answered

When you plucked a stretched string of a guitar, the air particles around it get set in vibration that creates alternate regions of low and high pressure.

This happens because, as the vibrating air moves forward and backward, it creates a low or high pressure region respectively.

Low pressure region is called rarefaction high pressure region is called compression.

Due to this reason sound propagates.

High density (medium molecule concentration is more) correspond to high pressure.

Low density (medium molecule concentration is less) correspond to low pressure.