用“伏安法”测电阻的实验中,电流表和电压表连入电路通常可以有两种方法,一种是如图1所示的电流表外接电路(简称“外接法”);一种是如图2所示的电流表内接电路(简称“内接法”).由于电流表和电压表内阻的影响,不论采用“外接法”还是“内接法”都将会引起测量误差.为了减小因电表的内阻而引起的测量误差,常根据被测电阻的估计阻值的大小(“低阻”或“高阻”)来选择不同连接方式的测量电路. “外接法”的测量误差是由于电压表的分流作用产生的, In the experiment of measuring the resistance with the “volt-ampere method”, there are usually two methods for connecting the ammeter and the voltmeter to the circuit. One is the external circuit of the ammeter shown in Fig. 1 (abbreviated as “the external method”); the other is The in-built current meter circuit shown in Fig. 2 (referred to as “inner connection method”). Due to the influence of the internal resistance of the ammeter and the voltmeter, whether or not the “external method” or the “inner method” is used will cause a measurement error. The measurement error caused by the internal resistance of the meter often depends on the size of the resistance of the measured resistance (“low resistance” or “high resistance”) to select the measurement circuit for the different connection methods. The measurement error of the “external method” is Due to the diversion effect of the voltmeter,