17.3. Millikan Oil Drop Experiment http://www.ck12.org
17.3 Millikan Oil Drop Experiment
- Explain how Millikan used electric fields to find the charge of the electron.
This is the original equipment used by Robert Millikan and Harvey Fletcher in 1909 at the University of Chicago
to measure the electric charge on a single electron. With incredible perseverance, they were able to determine the
charge to within 1% of the currently accepted value.
Millikan Oil Drop Experiment
The sketch below shows a diagram of theMillikan oil drop experiment. Two parallel charged plates are placed
with the positively charged plate above and the negatively charged plate below. The positively charged plate has a
pinhole opening in its center. An atomizer is used to spray drops of oil into the apparatus. The friction of the oil
passing through the narrow opening puts a charge on many of the oil drops. As the oil drops fall, one or more pass
through the pinhole opening and enter the area between the plates.