What was Milikan's primary achievement in his experiment?

Millikan's primary achievement in his experiment, known as the oil drop experiment, was to determine the charge of a single electron. In this groundbreaking experiment, he suspended tiny oil droplets in an electric field and balanced the gravitational and electric forces acting on the droplets. By carefully measuring how the droplets responded to the electric field, Millikan was able to isolate and measure the charge on a single electron. This work provided the first precise value for the elementary charge, which is fundamental in physics as it helps to form the basis of atomic structure and electrical interactions.

The significance of this achievement lies in its contribution to the understanding of atomic theory and electromagnetism, reinforcing the quantized nature of electric charge. Millikan’s measurement has been pivotal in the advancement of both theoretical and practical applications in physics.