指针式欧姆表的工作原理是闭合电路的欧姆定律,在讨论欧姆表时,一般是用教材上的原理图,它是一个单量程的欧姆表,只适用于×1挡位.当我们探讨欧姆表不同挡位的内阻时,应采用多量程欧姆表原理图.本文运用简化解析图指出:欧姆表各倍率挡的中值电阻并不是依赖于调零电阻的调节,而主要是靠改变并联电阻来调节,调零电阻仅起到微调的作用. Ohm’s law is the working principle of the closed circuit Ohm’s law in the discussion of the ohmmeter, the textbook is generally used on the principle that it is a single-range ohmmeter, only applies to × 1 gear.When we explore the ohm Table different block the internal resistance, should be used multi-range ohmmeter schematic diagram. This paper uses a simplified analytical map that: the ohmmeter each rate block the median resistance is not dependent on the adjustment of the zero resistance, but mainly by changing the parallel Resistors to adjust, zero resistance only play a role in fine-tuning.