Final answer:
The Millikan oil drop experiment is a physics experiment that measures the charge on individual oil drops. The charge is found to be quantized in units of -1.6 x 10-19 C.
Step-by-step explanation:
The subject of this question is Physics, specifically relating to the Millikan oil drop experiment.
The Millikan oil drop experiment was an important physics experiment conducted by Robert Millikan. In this experiment, oil drops were suspended in a vertical electric field against the gravitational force, allowing for the measurement of their charge.
The charge on the oil drops was found to be quantized in units of -1.6 x 10-19 C, which determined the charge of the excess and missing electrons on the drops.