Longitudinal Waves. To see a animations of spherical longitudinal waves check out: In a longitudinal wave the particle displacement is parallel to the direction of wave propagation. The animation at right shows a one-dimensional longitudinal plane wave propagating down a tube.
The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor.
1 Vapour pressure exerted by the vapours in equilibrium with liquid is known as equilibrium vapour pressure or saturated vapour pressure. 2  Temperature must be mentioned while reporting vapour pressure. 3  The vapor pressure of any substance increases non-linearly with temperature.