Kaplan Nursing Entrance Exam Practice 2025 – Comprehensive Prep

A longitudinal wave is characterized by particles of the medium moving in a direction that is parallel to the direction of the wave's energy propagation. This means that as the wave travels through the medium, the particles compress and then rarefy (stretch apart) in the same direction the wave is moving. This kind of motion creates areas of high pressure (compressions) and low pressure (rarefactions).

The option that states a wave exhibits repeating patterns describes a feature found in many types of waves, including both longitudinal and transverse waves, but it does not specifically define longitudinal waves.

A wave that vibrates in a direction that is perpendicular to the motion aligns with the definition of transverse waves, not longitudinal waves. Examples of transverse waves include light waves and waves on a string.

Lastly, stating that a wave is audible relates to specific sound waves, which are indeed longitudinal, but not all longitudinal waves are audible. This characteristic does not define what makes a wave longitudinal in nature.

Thus, the key defining characteristic of a longitudinal wave is found in the parallel motion of the vibrating particles relative to the wave direction.