J 38 Mr. Satyendra Ray on the 



Defining " magnetic polarization " in a manner analogous- 



to " electric polarization " as j- and representing it by o% 



and calling \ad$ for the whole of the equipotential surface m, 

 the Total Magnetic Pole, we have 



f 70 l T 1 /* V 3 i 1 • 3V 5 >1 . 3 . 5\ 2 7 , p 1 



or 



m = A{ive (ii.) 



where 



A Irl /1\ 2 3 /1.3\ 2 5 /l.3.5\ 2 7 , , • 



The series represented by A is a constant. We can call 

 it Ampere's Number. Physically we may define it as the 

 Magnetic Equivalent of Electricity, being the value of m 

 produced by unit electric charge moving with unit velocity 

 in a circle inside a medium of unit permeability. 



It will be noticed m is finite although H is infinite when 

 r=a. 



§ 3. Total Stress Energy. 



In terms of JBg?S for the surface of the equivalent mag- 

 netic shell the Total Stress Energy in the Magnetic Field 

 can be easily calculated. Integrating, tube by tube, from 

 the equipotential surface V=27r^ to the equipotential sur- 

 face V = 0, we have, if I is length of tube of induction 

 parallel to H, 



«wjj 



BrfS . dV ; 



t< —v, r—a 



\ I f ~^.dx.dy.dz=2.~ ( BdS . f 3 "jV 



~ATr 2 Afiar 



=A^t. .... (iii.) 



