A longitudinal wave is
characterized by rarefactions. A longitudinal wave is a wave motion wherein the
particles in the wave medium are displaced parallel to the advancing wave. When motion
is detected from the source, the particle next to it vibrates from its rest position
and a progressive change in phase vibration is observed at each particle within
that wave. The result is that the energy is transported from one region to the
other. These combined motions result in the movement of alternating regions of rarefaction
in the direction of transport of energy.
