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LIII. The Photoelectric Effect. By 0. W. Richardson 



and Karl T. Comptox, Princeton University *. 



[Plate XIII.] 



PROBABLY there is no line o£ investigation more likely 

 to lead to a correct understanding of the phenomena of 

 photoelectric aclion than a careful determination of the rela- 

 tions between the nature of the metal, the frequency of the 

 light, and the kinetic energy of the liberated elections. A 

 large amount of work has been done in the attempt to 

 determine these relations, but the results have been very 

 contradictory. For instance, von Baeyer and Gehrts f, and 

 Klages i found, in the case of several metals, that the maxi- 

 mum initial velocity of the electrons "was independent of 

 the metal used. Ladenburg§ and other physicists have 

 decided that the electronegative metals give off electrons 

 with the greatest velocities ; whilst Millikan and "Winchester || 

 concluded that the initial velocity bears no relation to the 

 "Volta series. Most physicists who have investigated the 

 subject believe that the maximum initial kinetic energy is a 

 linear function of the frequency of the light ; but some H 

 have obtained results supporting the view that the maximum 

 velocity varies as the first power of the frequency. 



The results of the present investigation show that there is 

 a much greater unity in the relations between different 

 metals and wave-lengths than has hitherto been supposed. 

 In fact, it will be shown that the important features of the 

 photoelectric behaviour of any metal are determined by a 

 single parameter characteristic of the metal. The parameter 

 has the dimensions of a frequency, and its significance will 

 be explained later. 



The first part of the paper is a discussion of the experi- 

 mental data. These data may be of value in testing any 

 theory of photoelectric action. In the latter part of the 

 ] taper the results are applied to test the theories of these 

 effects which have been developed by Einstein ** and by one 

 of the authors |t- 



* Communicated bv the Authors. 



t Per. der Deutsch Physik. Ges. xxi. p. 870 (1910). 



X Ann. der Physik, vol. xxvi. p. 343 (1909). 



§ Verh. der Deutsch Physik. Ges. ix. p. 504, ibid. p. 165 (1907) ; PJnjs. 

 Zeits. toL viii. p. 592 (1907). 



|| Phil. Mag. vol. xiv. p. 185 (1907). 



% Kunz, Phys. Rev. vol. xxxi. p. 536 (1910), vol. xxxiii. p. 208(1911). 



** Ann. der Physik, vol. xvii. p. 146 (1905). 



ft Phvs. Rev. vol. xxxiv. p. 146 (1912) ; Phil. Mag. vol. xxiii. p. 615 

 (1912) ; Science, vol.xxxvi. p. 57 (1912). 



