Simultaneous measuring the resistivity and permeability of a film sample with double coils

A method is proposed for a simultaneous measurement of the resistivity and permeability of a film by measuring the difference in the composite impedance of a pair of coils placed on both sides of the sample film facing each other. In first case, the current passes through the coils in the same direction and in second case, the current passes through the coils in opposite directions to each other. It was theoretically found that the optimum frequency for the measurement was proportional to the resistivity and inversely proportional to the thickness of a sample film in the case of paramagnetic films. This method was tested by measuring the resistivity of copper and brass films of a thickness ranging from 0.01 to 0.08 mm, and by simultaneously measuring the resistivity and permeability of nickel films of a thickness of 0.01 and 0.02 mm. The measured values of the resistivity with this method have correlated well with the values measured with the dc four-point probe method.<>