We report here the first attempt to test the results of cluster theory on a real, practical composite. For this purpose we have calculated the noise-power spectra of the capacitance between a riding capacitive probe and conducting composite using results of percolating-cluster theories. Comparison of the experimental results obtained on a carbon-black–polyvinylchloride composite confirms the predictions obtained from the above calculations. In particular it appears that the percolation-correlation length for composites can be estimated from the noise-power measurements.

• Received 24 September 1984

DOI:https://doi.org/10.1103/PhysRevB.31.8295