CHAPTER XIX. 



EADIATION FROM A RING OF ELECTRONS, AND ITS 

 BEARING ON THE CONSTITUTION OF AN ATOM. 



ALTHOUGH the radiating power of a single vibrating 

 or revolving electron is considerable, even when the 

 speed is not excessively high, it must be observed 

 that the amount of radiation emitted is greatly 

 diminished when a second symmetrically situated 

 particle is introduced ; because, at a distance, it will 

 be virtually in opposite phase to the first. The 

 diminution is specially marked when the speed is 

 low. In order to assist the radiation, the second 

 electron at the opposite end of a diameter should 

 be of opposite sign to the first. 



Three similar electrons at the corners of an equi- 

 lateral triangle will radiate much less than two ; and 

 so with every addition to a symmetrical system of 

 rotating particles, the radiating power diminishes ; 

 until when they form a continuous ring there is of 

 course no radiation emitted at all, since everything 

 is then continuous. 



Professor J. J. Thomson has calculated the amount 

 by which the radiation is diminished when the 

 number of particles is increased : and shown how 

 greatly it depends on their velocity. If they are 

 travelling with an orbital velocity of one-tenth the 



