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BELL SYSTEM TECHNICAL JOURNAL 



ductivity of ice provides a good example of this behavior, and Fig. 2 

 has been plotted to illustrate it, using data obtained by the writers 

 on the conductivity of ice at different temperatures. The leveling-off 

 of the conductivity curve at high frequencies is not observed in all 

 materials. For many materials the conductivity continues to increase 

 as the frequency becomes higher, though the rate of increase is often 



10 20 30 40 50 60 70 80 90 100 



FREQUENCY IN KILOCYCLES PER,SECOND 



Fig. 2 — The dependence of 7' upon frequency for ice at several different tem- 

 peratures.* The quantity 7' is the a-c conductivity less the d-c conductivity. The 

 curves show that the limiting value 7cd approached by 7' as the frequency increases is 

 lower the lower the temperature. 



* The curves of Figs. 2, 4 and 5 are drawn through experimentally determined 

 points. The experimental points are shown only where the curves should theo- 

 retically be linear or nearly linear. The fact that the points deviate by only com- 

 paratively small amounts from the theoretical curves in their linear sections is a 

 sufficient indication for the present purpose of the agreement between the theoretical 

 curves and the experimental data for ice. 



