# Millikan Oil Drop Simulation

Some years ago I wrote a little simulation program for a virtual Millikan Oil Drop lab. Since I have this Blog, I thought I would take the opportunity to share it, in hopes that others will find it useful as well.

It is a standalone Windows .exe file, with supporting documents in PDF. It allows students to practice using the apparatus using either droplets (random mass) or beads (fixed mass), and either the real value of e (1.6×10^-19 C) or an unknown value that is close to, but not quite, the real value.

There are a few nifty built-in features, like speeding up time and a stopwatch that follows the simulation time, plus the ability to adjust the plate spacing and reverse the polarity.

It’s not perfect, and the built-in help file doesn’t seem to display properly in Win7 (the Help.PDF file is the same as the online help), but it does the job adequately. The zip package includes a list of the unknown e values. I would suggest that if you distribute this package to your students that you remove the unknown e values.txt file, though that is up to you as a teacher.

The package can be downloaded here. It is distributed as-is, with no warranty.

If it is useful to you, enjoy!

## 13 thoughts on “Millikan Oil Drop Simulation”

1. yoko

Hello sir, i want to use your simulator to design any lab for the millikan experiment but i have no idea how to proceed. Can you give me a few suggestions please? For instance finding the relationship between the charge of beads and the potential difference V but i don’t know why to measure the time??? Can you give me an example where i can measure time please?? Reply asap please!!!!!

1. ed Post author

The purpose of the timer is to determine the terminal velocity of an oil droplet as it falls, if the power is turned off. Using beads, the mass is known, so this step is unnecessary.
Using the beads, the charge on a bead can be found by adjusting the voltage until the bead is stationary. The charge on the bead can be calculated using mgd/V. That charge should be a whole number multiple of e (1.6×10^-19).
Does that help?

2. sayaluthfi

excuse me Sir, i am Luthfi from Indonesia. i have problem when using this application. my computer can’t start the stopwatch and appear dialog box like that : ‘000.00’ is not a valid floating point value.
how to solve it? thanks Sir

1. ed Post author

Hi Luthfi, thanks for writing. I haven’t seen that, but it may be something with the settings in your operating system. Which version of Windows are you using, and what are your language/regional settings? I will see if I can replicate the error.

1. ed Post author

You want to find a voltage that will make the droplet hover in place. It may take a few tries to get the hang of it. Once it appears stationary you can speed up the time to make sure it is in fact stationary.

3. Sarwanto Sarwanto

Sir, Thank for your software of millikan oil drop. This is easy to use for my student, so I beg permission to use this software in my research.

1. ed Post author

What kind of research? Since this is of course a simulation, it can’t be used to prove anything. But if your research is on how people learn science, go for it!

4. Ivan Costa

Hi, same problem as Luthfi. Solved by turning on the power in the very beginning. I hope this helps. Regards. Ivan