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在中学物理教学中,光的量子学说是通过光电的实验来建立的,然而按课本(P271,图8-18)要求的用紫外线照射锌板使验电器指针张开的实验不易成功,于是人们不得不首先给锌板带上负电荷,再用紫外光照射,使验电器指针闭合,由此来说明光电效应。其实这不是一个好方法,它会使学生误解:认为这里的光电子是实验者给它预先带上的,而不是金属里原有的自由电子,没有这个附加条件光电效应就不能产生。究竟实验不易成功的原因是什么?怎样改进这个实验? 根据爱因斯坦方程 hv=A+1/2mV~2, 产生光电效应的必要条件是hv>A。我们所用的医用紫外光管发出光的波长为
In physics teaching at middle school, the quantum theory of light is established through the experiment of optoelectronics. However, according to the textbook (P271, Figure 8-18), the experiment of exposing the electroscope pointer with ultraviolet light is not easy to succeed. So people Have to first carry a negative charge on the zinc plate, then UV irradiation, the electroscope pointer is closed, to illustrate the photoelectric effect. In fact, this is not a good way, it will make students misunderstand: that the optoelectronics here is the experimenter to bring it in advance, rather than the original free electrons in the metal, without this additional condition, the photoelectric effect can not be generated. What is the reason why the experiment is not easy to succeed? How to improve the experiment? According to the Einstein equation hv = A + 1 / 2mV ~ 2, the necessary condition for the photoelectric effect is hv> A. We use the medical UV light tube emit light wavelength