Determination of the Electronic Charge by the Oil-Drop Method

Abstract

A NEW determination of the electronic charge e is being carried out using a method which is a development of the photographic method previously used¹. Instead of vertical plates and a horizontal field, horizontal plates are used as in Millikan's experiment. The present method has several advantages over the previous one. The path of the drop is now fifty or more times the distance measured, thus making the Brownian motion effect extremely small, and enabling effects due to a change in charge of the drop or evaporation readily detectable if they exist. An accurate study of the electric field can be made, and by photographing much smaller droplets a check can be made of the presence of convection currents. An interesting result has been obtained during the study of the field which may throw light on some of the previous oil-drop results, and so a brief report is made of this work.