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BELL SYSTEM TECHNICAL JOURNAL 



milky way. Semiconductors having a high po are Ukely to have a high 

 value of B and vice versa. If a series of semiconductors have points in Fig. 

 7 which fall on a straight line with a slope of 1/2.37^0 , they have a common 

 intercept in Fig. 3 for (l/T) = 0. 



6 



xlO'^ 



'"0 I 2 3 4 



B IN X AT 25t 

 Fig. 7.— Logarithm of the resistivity of various semiconducting materials as a func- 

 tion of B in equation (I). The quantity, B, is proportional to the temperature coefiicient 

 of resistance as given in equation (4). 



Physical Properties of Thermistors 



One of the most interesting and useful properties of a thermistor is the 

 way in which the voltage, F, across it changes as the current, /, through 

 it increases. Figure 8 shows this relationship for a 0.061 centimeter diam- 

 eter bead of Material No. 1 suspended in air. Each time the current is 



