Which term describes a region in which particles in a longitudinal wave are spread apart?

Which term describes a region in which particles in a longitudinal wave are spread apart?

• A. The part where particles are close together
• B. The crest
• C. The wavelength
• D. A part in a longitudinal wave where the particles are spread apart

Answer: (D)

In longitudinal waves, particles oscillate in the same direction as the wave travels, creating alternating regions where particles are compressed (closer together) and where they are spread apart. The region where particles are spread apart is known as a rarefaction. The description in the option matches this idea, describing a part of the wave where the particles are spread out. The other terms don’t fit this description: a crest is a peak in a transverse wave, and the wavelength is the distance between repeating points (like successive compressions or rarefactions), not the region itself. So the described region correctly corresponds to the idea of a rarefaction.

In longitudinal waves, particles oscillate in the same direction as the wave travels, creating alternating regions where particles are compressed (closer together) and where they are spread apart. The region where particles are spread apart is known as a rarefaction. The description in the option matches this idea, describing a part of the wave where the particles are spread out. The other terms don’t fit this description: a crest is a peak in a transverse wave, and the wavelength is the distance between repeating points (like successive compressions or rarefactions), not the region itself. So the described region correctly corresponds to the idea of a rarefaction.