Millikan Oil Drop Experiment

Scientists did not know about the electron or proton. They did not know how charges worked. Millikan believed all charges were multiples of a base charge. To find the value of this basic charge, he followed a similar solution to the Sklerocog Thought Experiment

Process

1. Drop randomly charged oil drops into an ionizer
2. The ionizer has a electric field that drags charges up
3. When the electrostatic force is equal to force of gravity, the oil drops would levitate
4. Keep adjusting the voltage until the oil drop levitated
5. Kept repeating several times with different oil drops

Result

Millikan found out $e=1.602\ast 10^{-19}$ which is the elementary charge