Which of the following is an example of a longitudinal wave?

• A. Water surface wave on a pond
• B. Light wave traveling through vacuum
• C. Wave on a stretched string
• D. Sound wave traveling through air

Answer: (D)

Verified step by step guidance

1. Understand the difference between longitudinal and transverse waves: In longitudinal waves, the particle displacement is parallel to the direction of wave propagation, while in transverse waves, the displacement is perpendicular to the direction of wave propagation.
2. Analyze each option: For a water surface wave on a pond, the particles move in circular or elliptical paths, which is characteristic of a transverse wave with some complexity, not purely longitudinal.
3. For a light wave traveling through vacuum, it is an electromagnetic wave, which is transverse because the electric and magnetic fields oscillate perpendicular to the direction of propagation.
4. A wave on a stretched string is a classic example of a transverse wave, where the string moves up and down perpendicular to the direction the wave travels along the string.
5. A sound wave traveling through air is a longitudinal wave because the air particles oscillate back and forth in the same direction as the wave travels, compressing and rarefying the medium.