When a sound wave passes through a medium, what happens to the particles of the medium?

• A. The particles remain completely stationary.
• B. The particles move in circular orbits as the wave passes.
• C. The particles move permanently in the direction of the wave.
• D. The particles oscillate back and forth parallel to the direction of wave propagation.

Answer: (D)

Verified step by step guidance

1. Understand that a sound wave is a mechanical wave that propagates through a medium by causing particles to vibrate.
2. Recall that in longitudinal waves, such as sound waves, particles of the medium oscillate parallel to the direction of wave propagation.
3. Recognize that the particles do not move permanently in the direction of the wave; instead, they oscillate back and forth around their equilibrium positions.
4. Note that the particles do not move in circular orbits; this behavior is characteristic of surface waves, not sound waves.
5. Conclude that the correct description is that particles oscillate back and forth parallel to the direction the sound wave travels.