# Millikan's Experiment- Oil drop containing an even number of charges

What error could occur if only a few oil drops were used, or if all the oil drops contained an even number of charges?

• -1 What do you think? We expect you to show the results of your own thinking, and to explain what difficulty you are having with the question. – sammy gerbil Dec 21 '17 at 2:35

If all the drops contained an even number of electrons (e.g. 2,6,22, and 100), you might look at the charges you measured and determine that the fundamental unit of charge was $2e$ (rather than $e$ which would be the correct answer).
If you only did a few drops, you might have bad luck and get ones that are all divisible by numbers larger than $e$. (maybe you got charges of roughly $7e$, $49e$, and $98e$, all of which are divisible by $7e$).
• I just did it a couple days ago for a class I'm preparing to teach for, and seeing drops up to $~25e$ was not uncommon. Depends on the oil used and the sprayer. (I may have been exaggerating with 98 though!) – Bunji Dec 21 '17 at 5:14