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Re: Millikan Apparatus- best one ?




On Wed, 9 Oct 1996, Leigh Palmer wrote:
Has anyone in this group ever had a student who succeeded in
demonstrating the quantization of charge doing this experiment?

Brad Shue wrote:

Leigh,
we do the Millikan every spring semester. When I do it, I get
very good results. ...
I can't give you any info on the actual data that the students
take because our current manual stinks and the experimental procedure
sucks. If done correctly, I have seen it to within 5% of the actual
value.

These comments remind me of a review I read many years ago in AJP
about the Pasco apparatus when it first came on the market. (I found
the reference in the AJP-TPT database: Haym Kruglak, AJP Vol. 40 #5 pp
768-76, May 1972) The reviewer said that in his opinion, most students
fail to understand the significance of the experiment. The main purpose
shouldn't be measurement of the electron's charge (which is what Brad
Shue refers to), but rather demonstration of the quantization of charge
(which is what Leigh Palmer refers to). When I ran across that review
in 1988, I was preparing to teach a modern physics lab which included
the Millikan experiment. I decided to try to get the students to
understand the quantization aspect of the procedure, but I'm afraid I
failed. Even after answering questions in the lab instructions and
hearing me tell them over and over about quantization, they concentrated
on the percent error and basically ignored the evidence of quantization
in discussions of their results. Oh, well...

Steve Luzader
Frostburg State University
sluzader@fre.fsu.umd.edu