Can Millikan's Oil Drop Experiment Accurately Measure the Elementary Charge?

AI Thread Summary
The discussion revolves around the accuracy of measuring the elementary charge using Millikan's Oil Drop Experiment. A participant encountered issues with their simulation results, which showed charges not being multiples of 1.6x10^-19 C. Feedback highlighted that the size of the oil drops was likely miscalculated, suggesting that a much smaller drop or fewer electrons per drop is necessary for accurate measurement. Participants noted that Millikan's original experiment managed to isolate only a few electrons on each drop, emphasizing the importance of precise measurements. The consensus indicates that the simulation used may not yield valid results for determining the elementary charge.
silentcoder
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Homework Statement


Hi, I had to calculate the charge of an oil drop using a lab simulation


Homework Equations


q = mgd/v


The Attempt at a Solution


This is the result i came up with:
Capture.png


The charges are not multiple of 1.6x10^-19 C. How can i fix this?

Thanks
 
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You realze I hope that even for your smallest oil drop you had about 2.9e-12/1.6e-19 = 18,125,000 electrons on that oil drop! And you expect to resolve to within 1 electron?

You need either a much smaller drop or, much more plausibly, you need to reduce the number of electrons on each drop. Millikan himself managed to put no more than about a dozen electrons on his drops.
 
You certainly use wrong units for the radius. Can you imagine a half-meter size drop of oil? How did you measure the size of the oil drops?

ehild
 
Last edited:
So it was simulation... Nice. Have you noticed that one scale is 0.5 mm? So the radii were wrong. Anyway, you can not get the electric charge with that simulation. It results too big charges, order of 10-12 C.

We did that experiment in real life when I was a student (about 50 years ago). We got several tens on electrons on a single drop, and then subtracted the charge values in hope that the smallest difference would be the elementary charge, but it never came out. So we did a very modern thing: We simulated the measurement data :wink: and then evaluated them. And we also wondered if Millikan really succeeded to obtain the elementary charge from his experiment.

ehild
 
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