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BELL SYSTEM TECHNICAL JOURNAL 



certain alcohols and glycols, the experimental points agree fairly 

 closely with the curves obtained by plotting equations (41a) and (416) 

 for a suitable choice of the values of the constants. 



But for many other dielectrics, particularly non-homogeneous 

 systems or disperse systems such as those listed under Item 3, Table I, 

 the simple dispersion formulae (41a) and (41Z>) often fall very far short 

 of adequately representing the experimental data. Von Schweidler "^^ 

 and Wagner ^^ have attempted to explain the form of dispersion curves 

 obtained for such materials by postulating that the polarizations 



•A 70 



P 40 



fJ 20 



10 50 100 500 1000 5000 10,000 



FREQUENCY IN CYCLES PER SECOND 



Fig. 3 — Experimental dispersion curves for ice. 



100,000 



induced in the dielectric have a wide range of relaxation times at any 

 given temperature, instead of a single relaxation time, as for the 

 polarizations listed in Table I. A further contribution to the theory 

 of the distribution of relaxation times has recently been made by 

 Yager .^^ However, in spite of the existence of many materials which 

 do not show the type of dispersion described by (41a) and (416), the 

 value of these formulae in interpreting experimental data is consider- 

 able, particularly as applied to pure materials. 



Table I emphasizes the point that mere agreement of experimental 

 data for dielectric constant and dielectric loss with the theoretical 



20 E. V. Schweidler, Ann. d. Phys., (4) (24), 711 (1907). 



21 K. W. Wagner, Archivf. Elektrotechnik, 2, 371 (1914). 



22 W. A. Yager, Physics, 7, 434 (1936). 



