waves
compression
Compression
density.
Rarefaction
vacuum or trough
waves
low density.
Compression is the region of a longitudinal wave in which the density and pressure are at a maximum. Rarefaction is the region of a longitudinal wave in which the density and pressure are at a minimum.
compression
Compression
Africa
density.
Jammu and Kashmir is a state in India; the population density is not so low for a region in the mountains - 56/km2.
Rarefaction
Arunachal Pradesh is a mounteneous region, terefore density of population is very low in Arunachal Pradesh.
An area of crowded particles followed by widely spaced particles is known as a density wave. In a density wave, particles are closely packed together in one region, creating a dense area, and then spread out and become less concentrated in another region, resulting in a sparse area. This pattern repeats periodically, forming a wave-like structure.