2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/151894It is shown that the notion of the finite pairing interaction energy range $T_d$ results in a linear temperature dependence of the London magnetic penetration depth $Δλ/ λ(0) = (T/T_d)(2/π)\ln 2$ at low temperature, in the case of the s-wave pairing state.5 pages, LatexSuperconductivitytext