# 100% transmission through a potential barrier

A particle of energy ##E## is incident upon a potential barrier of potential ##V_0## and of thickness ##a##. Given that ##E>V_0##, the transmission coefficient is given by

If destructive interference occurs when the path difference between the two reflected waves (at points ##x=0## and ##x=a##) is half-integral number of ##\lambda'##, then shouldn't constructive interference occurs when the path difference is integral number of ##\lambda'##?