Role of impurities in stabilizing quantum Hall effect plateaus

It is shown how the electromagnetic response of two-dimensional electron gas under quantum Hall effect regime transforms the sample impurities and defects in charge reservoirs that stabilize the Hall-conductivity plateaus. The results determine the basic dynamical origin of the singular properties of localization under the occurrence of the quantum Hall effect obtained in the pioneering works of Laughlin and of Joynt and Prange by means of a gauge invariance argument and a purely electronic analysis, respectively. The common intuitive picture of electrons moving along the equipotential lines gets an analytical realization.