Do Rayleigh waves travel along the surface of a material?

• A. They travel along the surface
• B. They travel through the bulk of the material
• C. They are the same as longitudinal waves
• D. They require a wedge to generate

Answer: (A)

Rayleigh waves propagate along the surface of an elastic solid, with their energy concentrated near the surface and decaying as you go deeper. The particle motion is a combination of vertical and horizontal movement, forming an elliptical path that stays close to the surface as the wave travels parallel to it. This surface confinement is what distinguishes Rayleigh waves from body waves, which travel through the interior of the material.

Because of that surface-focused nature, the statement that Rayleigh waves travel along the surface is the best description. They can be generated directly on the surface with a surface transducer or contact method, and they do not require a wedge to create them (wedges are used for other wave modes, like certain bulk or shear waves). They are not the same as purely longitudinal waves and they do not propagate through the bulk in the same way bulk waves do.