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在实验物理学、化学、天文学等等的科学领域中,常常要借助测量很微弱的电流来求得所要测定的量。如测量电离室中的电流来决定γ射线和伦琴射线的强度,测量质谱仪集电极上的离子电流来决定分析物所含某种元素的百分数,以及光度计中弱电流的测定等。所需测定的这些电流往往较10~(-11)安为小,而目前最灵敏的电流计只能测小到10~(-11)安的电流,并且振荡周期较长(约40秒);灵敏的静电计虽可以测
In the field of science of experimental physics, chemistry, astronomy and the like, it is often necessary to determine the quantity to be measured by means of a very weak current measurement. Such as measuring the current in the ionization chamber to determine the intensity of gamma rays and xanthones rays and measuring the ion current at the collector of the mass spectrometer to determine the percentage of an element contained in the analyte and the determination of the weak current in the photometer. The current to be measured tends to be smaller than 10 ~ (-11) A, while the most sensitive current meter can only measure current as small as 10 ~ (-11) A, and the oscillation period is longer (about 40 seconds) Sensitive electrometer can be measured