Differences in impedance result in which phenomenon at boundaries?

Differences in impedance result in which phenomenon at boundaries?

• A. Diffraction
• B. Reflection At Boundaries
• C. Attenuation
• D. Refraction

Answer: (B)

Impedance mismatch at a boundary between two media causes part of the incoming wave to bounce back into the first medium. Acoustic impedance, defined as density times wave speed, determines how much energy can cross the boundary. When the impedances differ, not all energy can transmit, so a reflected wave appears along with a transmitted wave whose speed and amplitude change according to the mismatch. The bigger the difference in impedance, the stronger the reflection. This is distinct from diffraction (bending around obstacles), attenuation (loss of energy as waves travel), and refraction (bending due to a change in speed), though refraction can occur alongside reflection when crossing a boundary.

Impedance mismatch at a boundary between two media causes part of the incoming wave to bounce back into the first medium. Acoustic impedance, defined as density times wave speed, determines how much energy can cross the boundary. When the impedances differ, not all energy can transmit, so a reflected wave appears along with a transmitted wave whose speed and amplitude change according to the mismatch. The bigger the difference in impedance, the stronger the reflection. This is distinct from diffraction (bending around obstacles), attenuation (loss of energy as waves travel), and refraction (bending due to a change in speed), though refraction can occur alongside reflection when crossing a boundary.