As the impedance difference between two media becomes very large, which phenomenon increases?

As the impedance difference between two media becomes very large, which phenomenon increases?

• A. Reflection
• B. Transmission
• C. Refraction
• D. Absorption

Answer: (A)

When a wave meets an interface with a large difference in acoustic impedance, reflection grows. The amplitude reflection coefficient is (Z2 − Z1)/(Z2 + Z1), and the energy reflection coefficient is its square. If the impedances are very different, this ratio approaches ±1, so nearly all the wave energy is reflected back into the first medium and little is transmitted. Refraction depends on the speed change (not the energy split) and can still occur, while absorption relates to material attenuation properties and is not directly driven by impedance mismatch. So, as impedance difference increases, reflection increases.

When a wave meets an interface with a large difference in acoustic impedance, reflection grows. The amplitude reflection coefficient is (Z2 − Z1)/(Z2 + Z1), and the energy reflection coefficient is its square. If the impedances are very different, this ratio approaches ±1, so nearly all the wave energy is reflected back into the first medium and little is transmitted. Refraction depends on the speed change (not the energy split) and can still occur, while absorption relates to material attenuation properties and is not directly driven by impedance mismatch. So, as impedance difference increases, reflection increases.