Physics307L F09:People/Long/Millikan

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Millikan Lab Summary

The purpose of the Millikan Oil Drop lab is to measure the charge of the electron using droplets of oil in free fall in an electric field. My partner Tom and I put forth our best efforts, but misunderstood the manual, which resulted in big time error.

Data Summary

Our results for the charge q of the electron are as follows:

Drop 1: 1.78(2)E-15 C

Drop 2: 1.24(3)E-15 C

Drop 3: 2.01(2)E-15 C

Drop 4: 6.58(3)E-16 C

Drop 5: 5.81(2)E-16 C

Drop 6: 8.16(4)E-16 C

Drop 7: 6.68(3)E-16 C

Drop 8: 3.40(2)E-16 C

Our values are much higher than the accepted value as given by the | Pasco manual which is 1.60E-19 Coulombs. The calculations and further data analysis for each of the eight trials is detailed in my lab notebook.


This is a pretty amazing and interesting experiment, kudos to Millikan for designing it. I learned that measuring the velocity of one of these oil droplets, can lead to the calculation of the mass of the droplet, the force due to the electric field, and thus the charge of the electron, I feel that I have a pretty good understanding of the experiment, but we used the voltage controller wrong, which lead to our heinous results.

Despite our unexpectedly high result for the charge, I learned a lot, mostly in the sense that taking your time and reading the manual a couple times over cannot hurt! I hate to complain, but the one thing I really despised about this lab was sitting for hours at a time straining my eyes trying to see the particles! A camera with monitor rig would be awesome.