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用电位计直接测量0.5μV以下的微小电势,由于检流计零位飘移(简称零位电势)及寄生电势的影响,有时测量误差可达1μV左右。零位电势和寄生电势是随着仪器工作条件的改变而变化的,所以采用电流换向及零电势补偿的方法,都难以消除两者的影响,故不能取得满意的测量结果。下面介绍一种偏差法可以较好地解决这一问题。使用这一方法时,电位计的最小步值应小于或等于0.1μV。测量时,将电位计工作电流标准化以后,调整检流计光电放大倍数,使检流计电压分度值为(0.01～0.001)μV/每格左右,按被测电势大约范围,在测量盘上预置一定数值,并记下检流计偏转格数(称为预置数
With a potentiometer to directly measure the micro potential of 0.5μV below, due to galvanometer zero drift (referred to as zero potential) and the impact of parasitic potential, sometimes measuring the error up to 1μV or so. Zero potential and parasitic potential with the instrument changes in the working conditions, so the use of current commutation and zero potential compensation method, are difficult to eliminate the impact of both, it can not get satisfactory measurement results. The following describes a deviation method can be a better solution to this problem. When using this method, the minimum step value of the potentiometer should be less than or equal to 0.1μV. Measurement, the potentiometer after the current standardization, adjust the galvanometer magnification, so galvanometer voltage divider value (0.01 ~ 0.001) μV / cell or so, according to the measured potential of about the range, in the measuring plate Preset a certain value, and note the deflection grid galvanometer (known as the preset number