By adjusting an electric field.
That should probably be "Millikan". The experiment he was famous for is the Millikan Oildrop Experiment.
His name was Robert A. Millikan.
Robert Millikan
Different drops had different charges in Millikan's oil drop experiment because they gained or lost electrons as they moved through the chamber, leading to variations in their net charge. This variability in charge allowed Millikan to observe different electrostatic forces acting on the drops and calculate the charge of a single electron.
Millikan was able to quantitate the elementary electric charge using his oil drop experiment. By measuring the forces acting on the oil drops in the electric field, he could determine the charge on each drop and eventually calculate the charge of a single electron.
Robert Millikan in 1909
He used voltage adjustments to make charged oil drops float
Drops of ethanol are attracted to a charged strip because ethanol is a polar molecule with a slightly positive and negative end. When a charged strip is brought near the drops, the positive or negative end of the ethanol molecule is attracted to the opposite charge on the strip, leading to the movement of the drops towards the strip.
es the rain drops have energy in the motion as they fall
In this experiment, the control group would be the penny! The independent variable is the substance/water on the penny, and the dependent is how many drops the penny takes.
Robert Millikan's oil-drop experiment involved suspending tiny oil droplets in a uniform electric field and measuring their motion to determine the charge of an electron. By balancing gravitational and electric forces on the oil droplets, he was able to calculate the charge of a single electron to be approximately 1.6 x 10^-19 coulombs. This groundbreaking experiment provided valuable insights into the fundamental properties of electrons.
There aren't a definite amount of drops in a volume. there are a few ways to control the size of a drop but it's not reproducible.