光电效应在物理教科书上一般是采用“带负电法”(即先给锌板带上负电荷,然后再用紫外线去照射的方法)来演示此实验的。如何使未带电的锌板在紫外线的照射下也能发射光电子,产生光电效应,并能由一般的验电器显示出来呢?为了解决这个问题,我们采用了“外加电场法”。 Photoelectric effects are generally used in physics textbooks to use the “negative charge method” (that is, first give the zinc plate a negative charge, and then use ultraviolet light to illuminate the method) to demonstrate the experiment. How to make an uncharged zinc plate emit photoelectrons under the irradiation of ultraviolet rays to produce a photoelectric effect, which can be displayed by general electroscopes? In order to solve this problem, we have adopted the “external electric field method”.