  We study the low frequency admittance of a quantum Hall bar of size much
larger than the electronic coherence length. We find that this macroscopic
conductor behaves as an ideal quantum conductor with vanishing longitudinal
resistance and purely inductive behavior up to f<1MHz. Using several
measurement configurations, we study the dependence of this inductance on the
length of the edge channel and on the integer quantum Hall filling fraction.
The experimental data are well described by a scattering model for edge
magnetoplasmons taking into account effective long range Coulomb interactions
within the sample. This demonstrates that the inductance's dependence on the
filling fraction arises from the effective quantum inertia of charge carriers
induced by Coulomb interactions within an ungated macroscopic quantum Hall bar.
