﻿THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



- ^ — 



[BiXTIi SERIES.] 



■ C.Sv / 



m 



V EMBER 1922. 



LXIX. The Emission of Electrons by X-Rays. By 

 Gr. Shearer. M.A., 1851 Exhibition Scholar, Emmanuel 

 College, Cambridge *. 



THE general object of this investigation was to obtain 

 more definite information as to the emission of 

 electrons from matter under the influence of X-ray bom- 

 bardment. 



(1) Historical. — Very shortly after the discovery of 

 X-rays it was shown that all forms of matter emitted 

 electrons when bombarded by X-rays. Later work revealed 

 the fact that, in this emission, the electrons had all velocities 

 up to a certain maximum ; this maximum velocity can be 

 determined by the quantum equations — 



±mv 2 = Ve = hv, 



where e, m, v represent the charge, mass, and maximum 

 velocity of the electrons, v the frequency of the X-rays, 

 V the applied potential, and h Planck's constant. 



In addition to this general electron emission, there is a 

 special emission associated with the characteristic X-radiation 

 of the matter bombarded. Until recently there has been 

 some doubt as to the exact nature of this special emission. 

 Experiments by Barkla and the author f failed to reveal any 

 special distribution of velocity associated with these electrons. 



* Communicated by Prof. Sir E Rutherford, F.R.S. 

 t Barkla and Shearer, Phil. Mag. xxx. p. 746 (1915). 



Phil. May. Ser. 6. Vol. 44. No. 263. Nov. 1922. 3 F 



