Transmission coefficient

The transmission coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered.All the meanings are very similar in concept: In chemistry, the transmission coefficient refers to a chemical reaction overcoming a potential barrier; in optics and telecommunications it is the amplitude of a wave transmitted through a medium or conductor to that of the incident wave; in quantum mechanics it is used to describe the behavior of waves incident on a barrier, in a way similar to optics and telecommunications.Although conceptually the same, the details in each field differ, and in some cases the terms are not an exact analogy.In chemistry, in particular in transition state theory, there appears a certain "transmission coefficient" for overcoming a potential barrier.The transmission coefficient is a measure of how much of an electromagnetic wave (light) passes through a surface or an optical element.[1] Consider a wave travelling through a transmission line with a step in impedance fromis uniquely determined from first principles by noting that the incident power on the discontinuity must equal the sum of the power in the reflected and transmitted waves: Solving the quadratic for[1] The value of the transmission coefficient is inversely related to the quality of the line, circuit, channel or trunk.The transmission coefficient is defined in terms of the incident and transmitted probability current density J according to: whereis the probability current in the wave incident upon the barrier with normal unit vectorThe reflection coefficient R is defined analogously: Law of total probability requires that[2][failed verification] In the classical limit of all other physical parameters much larger than the reduced Planck constant, denoted