348 Mr. Take Sone on the Magnetic Susceptibilities 



and independent of temperature. In Bohr's model *, we 

 have 



r = 0-525xl0- 8 cm., a> = 4'21 x : 10 16 /sec, 

 and therefore 



o- =l-117 xlO 1 , E.M.U. 



Hence, at a given temperature, the value of susceptibility 



71 



depends on ~KX2 2 . In order that the above expression 

 may give the observed value, we must take 



|Kf2 2 = 393-5xl0 10 ergs, 



or Oo = 6-54xl0 14 /sec. 



This angular velocity corresponds to the frequency 



y=l-04xl0 14 /sec. 



of the infra-red radiation. A similar expression holds also 

 for the susceptibility of other diatomic gases. 



According to Bohr, the helium atom has two positive 

 nuclei at the centre of the circular Orbit, in which two 

 electrons are revolving with a constant velocity. If we 

 assume that the helium atom has a similar structure to the 

 hydrogen molecule, in which two positive nuclei are situated 

 very near to each other, the atom may possess a similar 

 characteristic rotation as in the case of the hydrogen 

 molecule. We have then 



. x ~ 4?iKry 



According to Bohr, 



r = 0-318xl0- 8 cm., a> = 19 x lO^/sec. 



Therefore 



o- =l-81 xl0 3 E.M.U. 



In order therefore that the above expression may give a 

 value of susceptibility %= —11*0 X 10~ 6 , as actually observed 

 by Tanzler |, w r e must take 



^KO 2 =7-84xl0 10 ergs, 



or O = 3-80xl0 15 /sec. 



* N. Bohr, loc. cit. : P. Debye, loc. cit. 



t P. Tanzler, loc. cit. The present value is calculated from the 

 original value by taking v =104TxlO-°, 



