Question

what is compression and also rarefraction ?

Answer 1

However instead of crests and troughs, longitudinal waves have compressions and rarefactions. Compression. A compression is a region in a longitudinal wave where the particles are closest together. Rarefaction. A rarefaction is a region in a longitudinal wave where the particles are furthest apart.

Answer 2

Compression :-

Compression is a part of longitudinal wave in which the particles of the medium are closer to one another are normal and there is a momentary reduction in the volume of medium.

Rare fraction :-

Refraction is a part of a longitudinal wave in which the particles of medium are further apart than medium and there is a momentary increase in the volume of medium.

Eg:- soundwave.