密立根油滴实验问题三则

Three problems in Millikan oil drop experiment

密立根油滴实验在教学上依然存在诸多问题,比如元电荷的测量值偏差较大、元电荷的“目标函数法”求解方法问题以及油滴仪上紫外灯的使用等,若处理不好,会影响教学效果.本文认为元电荷的测量值偏差较大与显微镜分划板的准确性有关,也与实验者没有对油滴像调焦有关.“目标函数法”求解元电荷精度较高,本文对此用法进行了梳理,澄清了难点.紫外灯不能仅仅做为改变油滴电量的手段,本文从初始带有一个元电荷的油滴开始,通过测量每次电离之后的平衡电压,用电压的比值可以直观地证明电量量子化.

There are still many problems in Millikan oil drop experiment,such as the large deviation of the measured value of the elementary charge,the"objective function method"to solve the problem of the elementary charge,and the use of ultraviolet lamp on oil drops.If it is not handled well,the teaching effect should be affected.In this paper,the large deviation of the measured value of the elementary charge is considered to be related to the accuracy of the reticle of microscope and the fact that the experimenter does not focuses on the oil drop image.The objective function method is of high precision in solving the elementary charge.The usage is sorted out and the difficulties are clarified.Ultraviolet lamp can be used not only to change the electric quantity of oil drop,but also to directly prove the charge quantization by starting from the oil drop with an elementary charge at the beginning,then measuring the balance voltage after each ionization and using the ratio of voltage.