User:Darrell Bonn/Notebook/307L Lab book/lab Millikan Summary

From OpenWetWare
Jump to: navigation, search

Millikan Lab Summary

Lab Partner: Boleszek
Essential lab procedures were takne from the manual for the PASCO scientific Model AP-8210 "Millikan Oil Drop Apparatus" which can be found online here: 8210 Manual.pdf


To reproduce a measurement of the charge of an electron


The procedure is fairly well shown in our lab notes and in the 8210 manual bookmarked above. It takes a bit of time to get used to the device, but it is not too difficult to acquire decent data as is shown by our results.


Methods for calculating the charge are well documented in the apparatus manual pages 2 and 9. These techniques were used without modification.

During the lab, it was noticed that there were a high number of anomalous data. We decided that unless we could get three readings for both falling and rising times on a single drop, then we could not accept it as having value. Therefore, in the analysis, only those drops which had 3 or more readings for both rise and fall time were used for calculations. It would have been better to have decided this prior to beginning the lab, but it was experience with the lab which suggested this criterion for acceptable data. Althouh the criterion was established during data acquisition, it should be noted that it was established well before data analysis began and we therefore believe it to be an unbiased decision. We recommend that anyone else performing this lab set that criterion forward prior to begining.SJK 15:55, 18 December 2008 (EST)
15:55, 18 December 2008 (EST)
I think this is good reasoning, and likely unbiased, since you really had no clue what the actual charge number would be before the crunching.

All calculations were carried out in Mathcad as I expected to be able to save that to a file that could be directly uploaded as part of this page. It turns out that MHT files are prohibeted on wiki, so I have placed it in a word document instead. The calculations and summary are located there and can be opened by following this link: Millikan SummarySJK 16:00, 18 December 2008 (EST)
16:00, 18 December 2008 (EST)
Even combined w/ your final report, I'm still a bit confused as to how you guess the number of charges, or what you did there. Particularly in your last graph in the word document, where the guesses for 3 charges look more appropriate as 2 or 4.

As a final note, viscosity of air was calculated with the help of an online viscosity calculator