The electron, its isolation and measurement and the determination of some of its properties

by Robert Andrews Millikan

the known kinetic energy of the

-particle, then, since the inertias of the negative electrons are quite negligible in comparison with that of the

-particle, if the latter suffers an appreciable change in direction in passing through an atom it will be due to the action of the nuclear charge. If

represents the closest possible approach of the

-particle to the center of the nucleus, namely, that occurring when the collision is “head on,” and the