2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/151949The quantum theory for mesoscopic electric circuit is briefly described. The uncertainty relation for electric charge and current modifies the tranditional Heisenberg uncertainty relation. The mesoscopic ring is regarded as a pure L-design, and the persistent current is obtained explicitly. The Coulomb blockade phenomenon appears when applying to the pure C-design.REVTEX, no figures, talk at the Fifth International Wigner Symposium, Vienna 25-29 August, 1997Mesoscale and Nanoscale Physicstext