在光电效应实验教学中，通过测量不同频率下的截止电压，可以计算出普朗克常数，从而验证爱因斯坦光电效应方程的正确性，并加深对光的量子特性的理解.爱因斯坦的光电效应方程表明，截止电压是光频率的函数，而与光强度无关.然而，实验中发现截止电压的变化与光强度有关，因为光强度影响光电子的发射数量.不过，一旦达到饱和状态，光强度对截止电压便不再产生影响.此外，暗电流的存在也会影响截止电压的测量，带来误差.对这些因素的系统分析，有助于学生全面理解光电效应及其量子性质.

In the experimental teaching of the photoelectric effect, the Planck constant can be calculated by measuring the cutoff voltage at different frequencies, thus verifying the correctness of Einsteins equations and deepening the understanding of the quantum properties of light. Einsteins equation for the photoelectric effect shows that the cutoff voltage is a function of the frequency of the light and is independent of the intensity of the light. However, the change in cutoff voltage was found to be related to the light intensity, because the light intensity affects the number of photoelectrons emitted. However, once saturation is reached, the light intensity no longer affects the cutoff voltage. In addition, the existence of dark current will also affect the measurement of cutoff voltage, resulting in errors. Systematic analysis of these factors helps students to fully understand the photoelectric effect and its quantum properties.