初中第二册教材中“金属电阻率和温度的关系”的讲授,是以演示实验为基础来完成的.由于一般金属导体的电阻率和电阻的温度系数太小,因此课本介绍的实验装置的演示效果不够理想,尤其是小灯泡的亮度变化不显著.为此,我们利用一些废旧材料对实验作了一些改进,现介绍如下: The teaching of “relationship between metal resistivity and temperature” in the second volume of junior high school textbooks is based on demonstration experiments. Since the resistivity of the general metal conductor and the temperature coefficient of the resistance are too small, the textbook introduces the experiment. The demonstration effect of the device is not ideal, especially the brightness of the small bulb does not change significantly. To this end, we have made some improvements to the experiment using some old materials, which are now described as follows: