直流单臂电桥中保护电阻对测量精确度的影响是什么？ 为什么用直流单臂电桥测量电阻比用伏安法或万用表的欧姆档测量电...
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因为测量过程中保护电阻的阻值并不为零，故其本身也分担有电压。当检流计示数为零时，实际是有R1/(R2+Rh)=Rx/R0。故测得的Rx的阻值偏大.学术流
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