Thompson discovered electrons and proposed the plum - pudding model of the atom. Millikan measured the charge to mass ratio of an electron.
In the early days of the atomic theory, working with his cathode ray tube, J.J Thompson discovered electrons. His discovery of electrons led him to propose a model which depicted the atom as a sphere of positive charges into which negative charges were embedded. This is the plum-pudding model of the atom.
Using his famous oil-drop experiment, R.A Millikan successfully measured the charge to mass ratio of the electron and thereby determined the magnitude of charge on the electron.
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