Electrons and Electric Fields

The famous Millikan oil-drop experiment involved observing suspended minute oil-drops falling under gravity and then under an applied electric field which stopped the downward motion. There are quite a few descriptions of the experiment on the Internet, this being one of many.

There is a wee, ever so minor problem with the experimental setup and assumptions. This wee problem is the assumption that with the experimental electric field turned off, the only force acting on the oil-droplets is gravity.

What about the ambient electric field of the Earth itself?

None of the descriptions of the experiment make any mention of the Earth’s electric field, but do stress the presence of the far weaker gravitational field, and of course the far stronger electric field induced by the experiment design to stop the oil-droplets from falling under gravity.

About Louis Hissink

Retired diamond exploration geologist. Trained by Western Mining Corporation and polished by De Beers.
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