2.1.2　Indirect comparison

Indirect comparison is used to determine the quantity through an intermediate quantity or calculation by formulas.For example,one can get the unknown resistance Rx by indirect comparison to an adjustable standard resistance Rs,as shown in Figure 2.1.1.If the applied voltage U remains constant and the switch K is respectively connected to position 1 and position 2,we can obtain the value of Rx by adjusting Rs to the same current.

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Figure 2.1.1　Schematic diagram of indirect comparison method