The phenomenon by which a wave strikes a boundary and changes direction within the same medium is called?

The phenomenon by which a wave strikes a boundary and changes direction within the same medium is called?

• A. Divergence
• B. Impedance
• C. Angulation
• D. Reflection

Answer: (D)

When a wave meets a boundary and bounces back into the same medium, the wave is undergoing reflection. The key feature is that the direction changes at the boundary, but the wave remains in the original medium. For a smooth boundary, the angle of incidence equals the angle of reflection, so the beam appears to bounce off the surface. This is different from refraction, where the wave crosses into a different medium and changes direction while propagating within that new medium. The boundary’s impedance mismatch influences how much energy is reflected versus transmitted, but that detail explains the strength of the reflection rather than the basic phenomenon itself. In ultrasonic testing, reflections are what reveal interfaces or flaws because the returning echo indicates where a boundary lies.

When a wave meets a boundary and bounces back into the same medium, the wave is undergoing reflection. The key feature is that the direction changes at the boundary, but the wave remains in the original medium. For a smooth boundary, the angle of incidence equals the angle of reflection, so the beam appears to bounce off the surface.

This is different from refraction, where the wave crosses into a different medium and changes direction while propagating within that new medium. The boundary’s impedance mismatch influences how much energy is reflected versus transmitted, but that detail explains the strength of the reflection rather than the basic phenomenon itself. In ultrasonic testing, reflections are what reveal interfaces or flaws because the returning echo indicates where a boundary lies.