What type of wave is sound?

Sound is classified as a longitudinal wave because it travels through a medium (such as air, water, or solid materials) by compressing and rarefying the particles of that medium in the direction of wave propagation. In a longitudinal wave, the particle displacement is parallel to the direction of the wave's travel.

When a sound wave is produced, it creates areas of compression where particles are close together and areas of rarefaction where particles are spread apart. This movement allows sound to propagate effectively through various materials.

In contrast, transverse waves, such as light waves or waves on a string, involve particle motion that is perpendicular to the direction of wave travel. Surface waves, like those seen on water, have characteristics of both longitudinal and transverse waves and occur at the interface between different media. Electromagnetic waves, including visible light, are a distinct type of wave that does not require a medium for propagation and can travel through a vacuum.

Therefore, sound is correctly identified as a longitudinal wave due to its unique characteristics and the way it travels through different media.