322 



BELL SYSTEM TECHNICAL JOURNAL 



imposed a-c. voltages is measured on a single copper oxide disc at 

 various d-c. bias voltages, this impedance generally changes with 

 both bias and frequency. Measurements to 200 kilocycles made on a 

 3/16 inch diameter disc are shown in Fig. 4. At all negative bias 



0.3 

 0.2 



0.1 



0.05 



0.02 



^ 0.01 



100 



300 400 500 600 800 1000 



CAPACITY IN MICROMICROFARADS 



2000 



500 1000 5000 10,000 



RESISTANCE IN OHMS 



100,000 



Fig. 4 — Impedance of a copper oxide disc at various forward and reverse d-c. voltages 

 for small superposed a-c. voltage. 



