Simple percolation experiment in two dimensions

A simple experiment for the demonstration of percolation problems is reported. Following the method of Last and Thouless [B.J. Last and D. J. Thouless, Phys. Rev. Lett. 25, 1719 (1971) ], measurements were performed on a sheet of conducting paper after randomly cutting out small square “sites” at a concentration 1 — p. The conductance and the area fraction covered by the “infinite cluster” P were then evaluated as a function of p. This experiment, carried out at an undergraduate physics laboratory, appears to be appropriate as an introduction to the teaching of phase transitions.