A region where particles are crowded together.
Explanation
Sound waves propagate through a medium as longitudinal mechanical waves. This propagation occurs through the oscillation of particles back and forth parallel to the direction of energy transport, creating alternating regions of varying density and pressure known as compressions and rarefactions.
Detailed Analysis
- Compression: This represents a region in a longitudinal wave where the particles of the medium are crowded together. Consequently, this is a zone of high density and high pressure.
- Rarefaction: This represents a region where the particles are spread apart. This results in a zone of low density and low pressure.
Analyzing the options based on these definitions:
- A region where particles are spread apart.: Describes a rarefaction (particles spread apart).
- A region of low pressure.: Describes a rarefaction (low pressure).
- A region where particles are crowded together.: Correctly describes a compression (particles crowded together).
- A region where the density of the medium is minimum.: Describes a rarefaction (minimum density).
Key Takeaway: In a longitudinal sound wave, Compression is characterized by maximum density and pressure, while Rarefaction is characterized by minimum density and pressure.