The diffraction of cathode rays by thin films of copper, silver and tin

Abstract

The experiments to be described are a continuation of the work done by Prof. G. P. Thomson on the scattering of cathode rays by thin films. The details of the apparatus will be found in his paper. Cathode rays are generated in hydrogen in a discharge tube by an induction coil and pass through a fine tube at the end of which a film is mounted. The rays pass through this film and travel along the camera to the photographic plate which, when an exposure is to be made, is lowered into the path of the rays. The camera is exhausted along with the tube to a low vacuum by a three-stage mercury diffusion pump. The camera and anode are earthed, and the spark gap between two 4 cm. brass balls, which are connected directly across the tube, is read to give the potential through which the electron falls. A mercury break acts as interrupter in the primary and a rectifying valve is used in the secondary.