2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/148759The effect of the barrier on the proximity effect in normal-superconductor junction is analyzed. A general criterion for the barrier, though large, to be effectively transparent, is given. This criterion is applied to both the conductance of a disordered NS junction (reflectionless tunneling) and the density of states across it, showing that both phenomena stem from the same physical effect.RevTeX, 4 pages, 2 figures. References added, introduction revisedSuperconductivityMesoscale and Nanoscale Physicstext