Energy Distribution in Spectra. 



57 



(free from mercury vapour) at 4*63 mm. In the latter case 

 the background contributes such a large portion of the total 

 intensity in the vicinity of H 7 and H,s that the ratios S/y and 

 <y/{3 have not been shown in fig. 6, as the numbers were not 

 sufficiently reliable. 



Table II. 

 Pure dry Hydrogen free from Mercury Yapour. 



p in mm. 



•127 



•526 



1-1 



3 



4 



6 



8 



A. H^/Ha. 



25 



11-6 



5-8 



4-7 



4-4 



4-0 



4-8 



B. H/3/Ha. 



13-1 



9-4 



8-9 



9;3 



9-0 



8-5 



9-2 



A. Intensity Katios with background subtracted. 



B. Intensity Katios including background. 



Discussion of the Intensity Ratios. 



The Rutherford * hydrogen atom consists of a nucleus 

 with a single unit positive electric charge and an electron 

 with an equal negative charge. According to Bohr's t 

 theory of spectra, the electron may rotate in any one of a 

 series of circular orbits round the nucleus, the radii of 

 consecutive orbits or rings being as the squares of the 

 natural numbers. When the electron passes from ring 3 to 

 ring 2 the atom emits the red line H a . Similarly, in passing 

 from rings 4, 5, 6, to ring 2 the lines H^, H r , H 5 , respec- 

 tively, are emitted. The atom may pass from its normal 

 condition into any one of these states by collision with a free 

 electron which possesses a certain amount of energy. 

 Expressing this energy in terms of the potential difference 

 in volts through which the free electron must fall to acquire 

 it, w r e have the following relation between n and the energy 

 absorbed by the atom in reaching the different ring con- 



Igurations 



E = 



«& -a- 



Table III. 







E = energy 

 n = numbei 



absorbed by atom in volts. 



■ of ring in which the hydrogen 



electron 



revolves. 



E ... 



. . . 10-2 



12-1 12-7 



13-0 



13-6 



n . . . 



2 



3 4 



5 



inf. 









* Rutherford, Phil. Mag. xxi. (1911) p. 669. 



f Bohr, Phil. Mag. July, Sept, Nov. 1913, March 1914, Sept. 1915. 



