In what medium can longitudinal waves travel?

Longitudinal waves are characterized by the movement of particles in the medium parallel to the direction of the wave's propagation. This type of wave can travel through solids, liquids, and gases because all these states of matter have particles that can be compressed and rarefied, allowing the wave to transfer energy effectively.

In solids, longitudinal waves manifest as compressional waves, where atoms or molecules are close together and can easily adjust their positions, transmitting energy through the medium. In liquids, although the particles are more mobile than in solids, they can still compress and expand, allowing longitudinal waves to propagate. Gases, with their widely spaced particles, also allow longitudinal waves; in fact, sound waves in air, which are longitudinal waves, travel this way.

Thus, the ability of longitudinal waves to move through different states of matter is key to their classification. The answer illustrates this versatility, encompassing the full range of media where longitudinal waves can exist.