Millikan Oil Drop Experiment

The Millikan Oil Drop Experiment achieved the most precise direct measurement of the electron's charge in physics history. In 1909, Robert Millikan suspended charged oil droplets between two plates, measuring their motion under an electric field to calculate the fundamental charge as 1.592×10⁻¹⁹ C, within 99% of the modern value of 1.602×10⁻¹⁹ C. This work decisively proved charge quantization, outperforming #6 Galileo's Inclined Plane Experiments in precision by achieving uncertainties below 0.5% while Galileo's timing errors exceeded 5%. Each droplet's charge was always an integer multiple of that fundamental value, providing irrefutable evidence for atomic structure.