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Reflection, Transmission, Absorption

Discussion

Sound, for example …

Acoustic impedance, Z = ρv, is important when calculating the amount of reflection and transmission at an interface. For the reflected portion, notice that when Z₂ < Z₁, the sign of the reflected portion is negative, which indicates a change of phase.


R/A₀ = (Z₂ - Z₁)/(Z₂ + Z₁)		(reflected pressure amplitude)
T/A₀ = 2Z₂/(Z₂ + Z₁)		(transmitted pressure amplitude)

The Physics Hypertextbook

No condition is permanent.