transmission coefficient

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transmission coefficient (T) The ratio of the amplitude of a transmitted ray (A2) to that of the incident ray (A0), such that T = A2/A0. In the case of normal incidence, and in terms of the acoustic impedances (Z1 and Z2) of the two media above and below the boundary, T = 2Z1/(Z2 + Z1). Also, T = 1 − R, where R is the reflection coefficient. The transmission coefficient can also be expressed in terms of energy (T′), when T′ = 4Z1Z2/(Z2 + Z1)2.