Sensitivity and output formulas for the resistance bridge

IN EITHER the design or the application of a resistance bridge circuit, it may be necessary to calculate the output of the bridge in terms of input or vice versa. The purpose of the calculation may be to establish the required sensitivity of a galvanometer, meter, or of any other null detector or output device, which is to be energized by a resistance change in the bridge, or it may be necessary to determine the input voltage or current required for minimum operation. Upon occasion, an exact calculation may be required to calibrate the output indicator, as in the deflection types of resistance thermometer or strain-gauge bridges. The formulas and correction factors presented in Table I were developed by the author for convenience in performing such calculations.