Here's why:
* Longitudinal Waves: In these waves, the particles of the medium vibrate parallel to the direction the wave travels.
* Compression: When the wave passes, the particles are pushed closer together, creating a region of high density called a compression.
* Rarefaction: Immediately following the compression, the particles are spread apart, creating a region of low density called a rarefaction.
Think of it like a Slinky. When you push the coils together, you create a compression. When you pull them apart, you create a rarefaction.
