http://www.ck12.org Chapter 4. Atomic Structure
FIGURE 4.5
Plum pudding model of the atom.The Charge of the Electron
In 1909, Robert Millikan and Harvey Fletcher devised what is known as the oil drop experiment to determine the
charge of a single electron. The oil drop experiment consisted of an apparatus in which small, charged oil drops were
passed through an electric field. The electric field was created by two oppositely charged parallel metal plates. The
rate at which the oil drops fell through the field was used to determine the magnitude of the charge of an electron.
FIGURE 4.6
Millikan’s oil drop experiment.The following video illustrates this experiment and explains how the charge of an electron was determined: http://w
ww.youtube.com/watch?v=XMfYHag7Liw (1:14).
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