Answer:
Millikan's oil drop experiment proved that electric charge is quantized.
At the time, there was still great debate whether electric charge was continuous or not.
Millikan believed that there was a smallest unit of charge, and he set out to prove it.
This was the big result of the oil drop experiment.
That he could also determine the charge of the electron was a secondary benefit.
This was probably one of the most significant experiments ever carried out.
Explanation:
