The Electronic Charge

Abstract

THE determination of e by a new oil drop method in which the electric field is horizontal¹ has been completed. The expression for e in terms of the quantities measured is similar to that which applies to H. A. Wilson's method and is The correction for the departure from Stokes's law is obtained from Millikan's relation where e₁^a is calculated from (1) and pcm. of mercury is the pressure and a is radius of the drop (cm.). The oil drops used are larger than those used by previous experimenters, and their velocity of fall being large, their motion was recorded photographically using exposures of 0.0005 sec. at intervals of 1/25 sec. The velocity of free fall, v_gcm./sec. and the velocity in the direction of the electric field v_xcm./sec., could be estimated with satisfactory accuracy. The electric field was obtained by means of a stabilized rectifier designed by Mr. T. P. Gill² and was measured by potentiometer methods in terms of Weston cells calibrated by the National Physical Laboratory.