Variation of sound velocity through liquids with pressure

Abstract

The logarithmic variation of sound velocity with respect to the logarithmic variation of density through liquids is shown to be a constant equal to (c₁–1)/2 where c₁≡[d(1/β)//_dP]_T. An integrated formula is used to evaluate the velocities of sound at different pressures if the velocity of sound is known at atmospheric pressure. Further the logarithmic variation of sound velocity to the logarithmic variation of compressibility is nearly the same for all liquids, thus requiring that the plot of log u_l against log β should give a set of parallel lines with the same slope. Rao's ^{14, 15} empirical formula is explained in terms of c₁ which is connected to constants of the potential function governing the molecules of the liquid. Unlike Rao's formula the new relation is general and is independent of the nature of the liquid.