Which is an example of a longitudinal wave?

Which is an example of a longitudinal wave?

• A. Light
• B. Radio
• C. Sound
• D. Electromagnetic waves

Answer: (C)

Longitudinal waves are waves where the particle motion is parallel to the direction the wave travels, causing compressions and rarefactions as the wave passes through a medium. Sound fits this description nicely: in air (a medium) the air molecules move back and forth along the direction the sound wave is moving, creating regions of higher and lower pressure that propagate through the air. Light and radio waves, on the other hand, are electromagnetic waves. Their oscillations occur perpendicular to the direction of travel, and they can move through empty space. These are transverse waves, not longitudinal. So the example that shows a wave with motion in the same direction as the wave travels is sound.

Longitudinal waves are waves where the particle motion is parallel to the direction the wave travels, causing compressions and rarefactions as the wave passes through a medium. Sound fits this description nicely: in air (a medium) the air molecules move back and forth along the direction the sound wave is moving, creating regions of higher and lower pressure that propagate through the air.

Light and radio waves, on the other hand, are electromagnetic waves. Their oscillations occur perpendicular to the direction of travel, and they can move through empty space. These are transverse waves, not longitudinal.

So the example that shows a wave with motion in the same direction as the wave travels is sound.