Abstract
The ac quantum Hall resistance of several GaAs-based samples has been investigated. The influence of temperature, current and frequency was measured for the plateau i = 2. Some measurements were performed for the plateau i = 4 in order to determine the scaling behaviour with respect to i. The plateau edge is shown to depend on the electronic temperature and the current at the plateau edge is distributed over the whole width of the sample. At the plateau centre, edge-current effects become apparent which depend on how close the filling factor is to an integer value. The losses of these edge currents cause the ac quantum Hall resistance to differ from the dc quantum Hall resistance.