The oil drop experiment is a famous scientific experiment conducted by physicist Robert A. Millikan in the early 20th century. Its primary purpose was to measure the elementary electric charge (the charge of a single electron) and to confirm the quantization of electric charge. Here'sa brief overview of how the experiment worked: 1. **Setup**: Millikan created a fine mist of oil droplets, which he then passed through an atomizer. These droplets were small enough to exist as individual entities.