What is the difference between a compression and a rarefaction in a sound wave? Illustrate your answer with a sketch.

In a sound wave, compression and rarefaction are two fundamental components that represent regions of varying pressure and density. These components create the characteristic pattern of a longitudinal wave, which is how sound travels through a medium, such as air.

Compression:

Compression refers to the region of a sound wave where air particles are pushed together, leading to an increase in pressure and density.
In a compression, the air particles are closer together than they are in the undisturbed, equilibrium state.
It corresponds to the high-pressure regions of the sound wave.
Think of it as the "peak" or "crest" of the wave.
Rarefaction:

Rarefaction is the opposite of compression. It refers to the region of a sound wave where air particles are spread apart, resulting in a decrease in pressure and density.
In a rarefaction, the air particles are farther apart than they are in the equilibrium state.
It corresponds to the low-pressure regions of the sound wave.
Think of it as the "trough" or "valley" of the wave.