What type of wave can travel through a medium and is defined by compressions and rarefactions?

A wave that travels through a medium and is characterized by compressions and rarefactions is known as a longitudinal wave. In these types of waves, the particles of the medium move back and forth in the same direction as the wave is traveling. This movement creates regions where the particles are close together, called compressions, and regions where they are spaced apart, known as rarefactions.

For example, when a sound wave travels through air, it compresses the air molecules in areas of high pressure and rarefies them in areas of low pressure, allowing the sound to propagate through the medium. This direct interaction of particles in the medium is a defining feature of longitudinal waves, distinguishing them from other wave types, such as transverse waves, where particle motion is perpendicular to the direction of wave travel.