测电源的电动势和内阻实验的误差分析一直是高中物理电学部分的难点.笔者在教学中发现利用图象法来分析本实验的误差有着非常直观、简洁的特点.现总结如下.1.内接伏安法测电源电动势和内阻的误差如图1所示,根据闭合电路欧姆定律:E=U+Ir,即U=E-Ir.如图2所示,本实验的误差主要来自电压表的分流,当电压为U_1时,实际流过电源的总电流比电流表的读数多出了△I_1=U_1/R_V;当电压为U_2时,实际流过电源的总电流比电流表的读数多出了△I_2=U_2/R_V.因为U_1< Measuring the power of the emf and resistance experiment error analysis has been the high school physics part of the electrical difficulties.I found in teaching the use of image method to analyze the error of this experiment has a very intuitive and concise features are summarized as follows According to the closed circuit Ohm’s law: E = U + Ir, namely U = E-Ir. As shown in Fig. 2, the error of this experiment comes mainly from the voltage When the voltage is U_1, the total current actually flowing through the power supply exceeds the ammeter reading by ΔI_1 = U_1 / R_V. When the voltage is U_2, the total current actually flowing through the power supply is more than the ammeter reading △ I_2 = U_2 / R_V because U_1 <