In this Activity, students simulate Millikan’s oil drop experiment using drop-shaped magnets and steel BBs. Students determine the mass of a single BB analogous to the way Millikan determined the charge of a single electron. This is a good Activity to use after a discussion of the concept of atoms, including identification of electrons, protons, and neutrons, and how atoms of one element are different from the atoms of another. This is often done early in the course with a discussion of Dalton’s atomic theory.
Earl F. Pearson, J. Chem. Educ. 2006, 83, p1312A.