What is an example of a longitudinal wave?

What is an example of a longitudinal wave?

• A. Radio wave
• B. Sound
• C. Light
• D. X-ray

Answer: (B)

Longitudinal waves involve the motion of the medium’s particles in the same direction as the wave travels. In air, sound travels as a series of compressions (where air molecules are crowded together) and rarefactions (where they're spread apart). The particles move back and forth along the path the wave is moving, creating those pressure differences that propagate the wave forward. That mechanical, particle-oscillation-along-the-path nature is what makes sound a classic example of a longitudinal wave. The other options are electromagnetic waves, which are transverse. Their oscillations occur perpendicular to the direction of travel and they can propagate through empty space without a medium. So they don’t fit the longitudinal pattern of particle motion along the propagation direction.

Longitudinal waves involve the motion of the medium’s particles in the same direction as the wave travels. In air, sound travels as a series of compressions (where air molecules are crowded together) and rarefactions (where they're spread apart). The particles move back and forth along the path the wave is moving, creating those pressure differences that propagate the wave forward. That mechanical, particle-oscillation-along-the-path nature is what makes sound a classic example of a longitudinal wave.

The other options are electromagnetic waves, which are transverse. Their oscillations occur perpendicular to the direction of travel and they can propagate through empty space without a medium. So they don’t fit the longitudinal pattern of particle motion along the propagation direction.