Millikan was able to follow the motion of a given droplet for many hours on end, using its electric charge as a handle by which to pull it up or down at will. In the course of such protracted observations, the charge on the drop would often change spontaneously, and several different values of terminal velocities would be obtained.

Source: Wikipedia Oil Drop Experiment A fine mist of oil droplets was sprayed into a chamber above the plates. The oil was of a type usually used in vacuum apparatus and was chosen because it had an extremely low vapour pressur

2022年9月20日 · The electric field in the Millikan oil drop experiment uses a downward electric field so that negative ions (added electrons) feel an electric force opposing gravity. Positive ions would experience a downward net force and quickly accelerate out of view. If the electric field were upward, then only positive ions would be visible.

2017年12月24日 · Moreover, in Millikan's real experiment (rather than the simplified version presented in many basic treatments) you watch a drop while for long enough to record one or more instances of the drop's charge being reduced (an effect of cosmic radiation), so you can observe the steps down toward neutral.

2021年4月4日 · When you do Millikans experiment you don't know n or what two neighbouring groups are. The experiment shows, with enough droplets measured, that you get only multiples of some Number approximately 1.6*10^-19 As to really measure e with some accuracy this is not the best experiment.

2023年6月25日 · Millikan measured the time for a droplet to fall a particular distance under the influence of gravity and aerodynamic drag, then switched on his electric field and measured its travel time over a similar distance under the influence of gravity, drag, and the field.

2018年2月7日 · Here is an example of what one gets in measuring the charge with a Millikan oil drop experiment, designed for physics students at university level. Just 12 measurements of the charge carried by the drops are shown, already fallen into groups, as seen in this plot.

2012年2月28日 · I remember while learning about Millikan's oil drop experiment and being pretty skeptical about the setup. I know that there is a lot of controversy regarding manipulation of data, but the fact is; he still got a pretty close answer.

2020年5月12日 · This means for this experiment to make any sense, the oil drops must be negatively charged. If this is the case, then why are X-rays used to cause the oil droplet to be charged? Surely since X-rays are ionising, they would remove electrons, making the oil droplets positively charged.

2022年6月13日 · Millikan is aiming for about four significant figures of precision. Since $\frac\rho\sigma≈10^{-3}$ , you only need about two significant figures on $\rho$ to get adequate precision in the difference.