高中物理课本在讲到光电效应时,首先介绍了这样一个实验:把一块擦得很亮的锌板连接在灵敏验电器上,用弧光灯照射锌板(图1),验电器的指针就张开一个角度,表示锌板带了电,进一步检查知道锌板带的是正电。这说明在弧光灯的照射下,锌板中有一部分自由电子从表面飞了出去,锌板中缺少 When the high school physics textbook talked about the photoelectric effect, it first introduced such an experiment: Connect a brightly polished zinc plate to a sensitive electroscope, and use an arc lamp to illuminate the zinc plate (Figure 1). The pointer of the electroscope will be opened. At an angle, it means that the zinc plate has electricity, and further inspections will know that the zinc plate is positive. This shows that under the irradiation of the arc lamp, a part of the free electrons in the zinc plate flew out of the surface, and the zinc plate was missing.