一、问题的提出在伏安法测电源电动势和内阻的实验中 ,有如图 1和图 2所示的两种电路可供选择 ,两种接法都存在较大的难以克服地系统误差 .1 .图 1中 ,由于电流表内阻 RA 有分压作用 ,使电压表读数小于路端电压 ,而且电流表内阻 RA 越大 ,分压作用越明显 ,误差就越大 .2 .图 2 First, the problem proposed in the volt-ampere test EMF and internal resistance of the experiment, there are two kinds of circuits shown in Figure 1 and Figure 2 to choose from, the two methods are there is a large system of insurmountable errors. 1. In Fig. 1, due to the partial pressure of the internal resistance RA of the ammeter, the voltmeter reading is less than the voltage of the road terminal, and the greater the internal resistance RA of the ammeter is, the more obvious the partial pressure is, and the larger the error is.