The Millikan Oil Drop Experiment is an experiment conducted by Millikan in 1909. At that time, electrons had been discovered, but it was not yet known what the amount of power was. Millikan's oil droplet experiment not only measured the charging capacity of the electron, but also found that the charging capacity of the oil droplet is an integer multiple of a certain value, and this minimum value is called the meta charge. This is the discontinuity of the charge, which can also be called the quantization of the charge.
The discovery of meta-charge and charge quantization is a major event in the history of physics, and Millikan won the 1923 Nobel Prize in Physics for this experiment. However, the Millikan experiment only uses a very simple experimental device, and many schools' university physics experiments currently have experiments that use oil droplet experiments to measure the charge of elements. Making such a big discovery with a very simple device is absolutely very handsome! It was absolutely beautiful!
Millikan experimented with some charged oil droplets in the electric field, and the oil droplets were chosen to reduce evaporation. These charged oil droplets are subject to gravity, electric field forces and air resistance, and through simple conversion, the number of charges carried by the oil droplets can be obtained, and until now, new physics has not yet been born. Fortunately, Millikan was a very thoughtful physicist, and after measuring many different oil droplets accordingly, he also came up with his "insight", and he found that the total charge values of the oil droplets are all multiples of the same number.
Today we know that this number is the meta charge (the amount of charge of the electron e), and Millikan's experiment proved the characteristics of charge quantization, for which he won the 1923 Nobel Prize in Physics. The "beauty" of this experiment is that it measures the microscopic (quantized) charge with some macroscopic matter (oil droplets), and the means of the experiment are relatively simple, but this experiment also has many problems.
There are two important controversies about the Millikan experiment, on the one hand, Millikan did not let his graduate student (Harvey Feltcher) sign this important paper, resulting in his students not being able to share the Nobel Prize; on the other hand, many other contemporaries could not repeat the results of the Millikan study, Mirigan died in 1953, after his death, the researchers "declassified" the Millikan experimental records, found that Millikan seemed to have "academic misconduct".
In the original records of his experiments, his measurements were screened, about half of the data was discarded, and the reasons for the data exclusion were many: the instrument was not working properly, it seemed that a high-order correction of the air resistance term was required, it did not meet expected expectations, abnormal results, and so on. Some of these reasons still seem reasonable, but reasons like "not meeting expectations" can be a bit hard to accept, and they do violate our academic norms today, and we need to be careful that this "insight" may also be some kind of preconceived "bias".
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