At a certain point of a travelling sound wave, the instantaneous excess pressure is positive, so Δp > 0. Which statement correctly identifies the local state of the medium?
Options

Question

At a certain point of a travelling sound wave, the instantaneous excess pressure is positive, so Δp > 0. Which statement correctly identifies the local state of the medium?

G1 Physics · Accepted Answer

A compression is a region where the particles of the medium are crowded closer together than at equilibrium. Therefore, in a compression, Δρ > 0 and Δp > 0. A rarefaction corresponds to Δρ < 0 and Δp < 0. Thus positive excess pressure identifies a compression. Correct option: B.