Abstract: A novel liquid conductivity measurement method based on the principle of bridge balance is proposed. The accuracy of conductivity measurement is affected by inherent capacitance and spontaneous electromotive force of liquid, which are encountered in conventional testing processes. To mitigate the interference caused by capacitance, high-frequency alternating current is employed instead of direct current. Additionally, an oscilloscope is used as a replacement for a galvanometer optimizes the criteria for bridge balance determination. Specifically, the oscilloscope indicates a non-zero linear signal as the reference for bridge balance. Based on this method, it is observed that the concentration of sodium sulfate solution exhibits a linear relationship with its conductivity. The relative uncertainty can be reduced to as low as 1.8%. This finding can be successfully applied in blind predictions of unknown solution concentrations and simulated rainfall amounts.

Key words: liquid conductivity, balanced bridge, electromotive force, capacitance