Small Electric Currents [Fundamentals of Measurement]

The values of electrical quantities span over an incredibly wide range. In the same laboratory, one can manage the measurement of, say, both small 1 pF capacitors and of 1000 F supercaps for energy storage. Conductors ask for measurement of resistances in the milliohm; insulator resistance can go up to several teraohm. A range of 15 orders of magnitude seems normal—until one considers that the same range for a length measurement, for example, would go from the size of a bacterium to a journey to the moon. Technological development pushes the need for accurate measurements of electrical quantities at the extremes of these ranges.