人民教育出版社出版的初中物理第二册第49页图4－9和50页图4－12所示的演示实验，用导电能力较强的导体实验时，现象明显，但用导电能力较差的导体实验时，现象不太明显，甚至小灯泡不发光。笔者曾用灵敏电流计代替灯泡作上述实验，实验现象虽然明显了一点，但由于学生求学习电 The junior high school physics book published on the 49th page of the junior high school physics book published by the People’s Education Press shows the demonstration experiment shown in Fig. 4-12. When the experiment was conducted with a conductor with high conductivity, the phenomenon was obvious but the conductivity was poor. In the conductor experiment, the phenomenon was not obvious, and even a small light bulb did not emit light. The author used the sensitive ammeter to replace the light bulb for the above experiment. Although the experimental phenomenon is obviously a little, but because students want to learn electricity