Which is an example of a longitudinal wave?

Which is an example of a longitudinal wave?

• A. X-ray
• B. Light
• C. Sound
• D. Gamma ray

Answer: (C)

Longitudinal waves involve particle motion parallel to the direction the wave travels. In air, sound propagates as regions of compression and rarefaction, with air molecules moving back and forth along the path of the wave. That back-and-forth movement in line with the travel direction is what characterizes a longitudinal wave. By contrast, light, X-rays, and gamma rays are electromagnetic waves. They are transverse, meaning the oscillations occur perpendicular to the direction of travel, and they can propagate through space without a medium. Because the medium’s particles don’t move along the wave’s path with EM waves, these are not longitudinal. So among the options, sound is the example of a longitudinal wave.

Longitudinal waves involve particle motion parallel to the direction the wave travels. In air, sound propagates as regions of compression and rarefaction, with air molecules moving back and forth along the path of the wave. That back-and-forth movement in line with the travel direction is what characterizes a longitudinal wave.

By contrast, light, X-rays, and gamma rays are electromagnetic waves. They are transverse, meaning the oscillations occur perpendicular to the direction of travel, and they can propagate through space without a medium. Because the medium’s particles don’t move along the wave’s path with EM waves, these are not longitudinal.

So among the options, sound is the example of a longitudinal wave.