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Re: Oh no! The definition of weight again!



On Fri, 12 May 2000, Bob Sciamanda wrote:

Suppose I weigh an oil drop (of known charge) by using the Millikan
apparatus to read the required levitating electric field? Do I directly
read the force of the drop on the apparatus?

Perhaps I am missing the point here. (It has been a *very* long week.)
In the Millikan oil drop experiments that I have done, you directly read
the indication of some kind of voltmeter. You can then use that reading
(along with other information) to determine the force of the drop on the
apparatus although you are more likely to think of what you are doing as
determining the gravitational force exerted on the drop. If you were to do
the experiment in a reference frame that accelerates differently from the
ground in your vicinity, I suppose you would be less likely to think the
latter and, perhaps, more likely to think the former.

John Mallinckrodt mailto:ajm@csupomona.edu
Cal Poly Pomona http://www.csupomona.edu/~ajm