Measurement of resistance ratios in the range to 100 megohms

The results of using a technique of potentiometrically comparing the voltage drops across two resistors in series utilizing an automatic potentiometer are presented. It is shown that a source voltage of 10 V is adequate to make 1:1 ratio resistance measurements from 10/sup 3/ Omega to 10/sup 8/ Omega to within +or-0.5*10/sup -6/. The same source voltage of 10 V can be used to make 10:1 ratio measurements from 10/sup 3//10/sup 2/ Omega to 10/sup 8//10/sup 7/ Omega to within +or-1*10/sup -6/. The source voltage of 10 V can also be used to make 100:1 ratio measurements from 10/sup 5//10/sup 3/ Omega to 10/sup 8//10/sup 6/ Omega to within +or-6*10/sup -6/. Ratios of 1:10 can also be measured. but in general the anticipated uncertainty is some 2-5 times greater than when a 10:1 ratio is measured. >