Explain Millikan's oil drop experiment and how it led to the measurement of the electron's charge.
Match the words in the left column to the appropriate blanks in the sentences on the right.
emit
upper
emitted electrons because of
acquired electrons produced
by
contain
positively
negatively
two
three
lower
electric force
gravity
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In this experiment, a closed chamber fitted with parallel metal plates acquiring a positive
or negative charge when an electric current is applied to them is used. In the beginning, an atomizer
sprays oil into fine droplets in the portion of the chamber. The droplets move under the
influence of through a small hole in the upper metal plate into the portion
of the apparatus. During their movement, the drops bombarding the air in the chamber
with ionizing radiation. Since the plate was negatively charged, and since Millikan could
vary the strength of the electric field, he could slow or even reverse the movement of the
charged drops. By measuring the strength of the electric field required to halt the free
movement of the drops and by figuring out the masses of the drops themselves, Millikan calculated the
charge of each drop. He then reasoned that, since each drop must an integral number
of electrons, the charge of each drop must be a whole-number multiple of the electron's charge.
