Open AccessThe transmission of cathode rays through matter
Publication year - 1914
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1914.0023
Subject(s) - cathode , intensity (physics) , radiation , brightness , absorption (acoustics) , optics , traverse , beam (structure) , physics , x ray , radiant intensity , chemistry , geology , geodesy
The experiments of this paper are the outcome of an attempt to discover whether cathode rays are selectively absorbed when their speed is sufficient to excite the radiation characteristic of the material they traverse. The general laws of absorption of cathode rays were elucidated many years ago by Lenard,* and the law which bears his name is expressed by the relation I = I0 e -λx, where I0 is the " intensity " of a beam of cathode rays incident on an absorbing sheet of thicknessx , and I is the "intensity" of the emergent rays. The intensity, as measured by Lenard, was indicated by the brightness of a phosphorescent screen struck by the rays. In the above formula λis the absorption coefficient. For a definite initial speed of ray λ/ρ is constant, ρ being the density of the absorbing material, while for any material Lenard found that λ varied inversely as the fourth power of the speed the rays.