In a longitudinal pressure wave, how do the particles move?

• A. Perpendicular to the wave direction
• B. In a circular motion
• C. Parallel to the direction of the wave
• D. Randomly

Answer: (C)

In a longitudinal pressure wave, particles move parallel to the direction of the wave. This type of wave is characterized by compressions and rarefactions, where the medium's particles oscillate back and forth in the same direction as the wave is traveling. When a wave travels through a medium, such as air or water, the particles experience alternating phases where they are compressed together during compressions and spaced apart during rarefactions. This motion effectively transmits the energy of the wave through the medium.

Therefore, understanding that in longitudinal waves, the particle movement aligns with the wave’s direction helps clarify why the correct answer pertains to the parallel movement of particles in relation to the wave direction.