全日制高中物理教学大纲所规定的学生实验之一——用安培表和伏特表测定电池的电动势和内电阻。从历届学生完成情况来看,所得数据的相对误差远远超过10％。在实验中我们考虑到干电池内阻较小,为了使电压表有较明显的变化,给干电池串联了一只5欧的定值电阻,用以增大干电池的内电阻。实验结束时,在得出内电阻之前还得减去串联的5欧电阻,减的结果有些实验小组竟会出现负值。所以说,对此实验要 One of the student experiments specified in the syllabus for full-time high school physics—the amperometric and voltmeters are used to determine the electromotive force and internal resistance of the battery. From the completion of previous students, the relative error of the data obtained far exceeds 10%. In the experiment, we consider that the internal resistance of the dry battery is small. In order to make the voltmeter have obvious changes, a fixed resistor of 5 ohms is connected in series with the dry battery to increase the internal resistance of the dry battery. At the end of the experiment, the series resistance of 5 ohms was also subtracted before the internal resistance was obtained. The result of the deduction was that some of the experimental teams actually had negative values. So say this experiment