INDUCTANCE AND CAPACITY 413 



which induces in the secondary an e.m.f. in quadrature with the 

 primary current. These two components of the electromotive 

 force in the secondary must be added, and obviously the result- 

 ant electromotive force will not be in quadrature with the primary 

 current. To illustrate further, the current in the primary, 

 Fig. 240, is /. This is supposed to induce an e.m.f. in the sec- 

 ondary which is represented by jmul. Let e represent the 

 path of the eddy current ; its mutual inductance with respect to 

 the primary is mi and with respect to the secondary is m*. 



FIG. 240. Pertaining to eddy current errors in mutual inductance bridge. 



The e.m.f. induced in the eddy-current circuit by / will be 



E e = - jm^L 

 The corresponding current will be 



7? T 70)7 * 



I e will induce an e.m.f. in the secondary, given by 



#'*=- 



R e + juL e Re + j^e 



= I ( p 2 2r2 - ) 



V R e 2 + C0 2 L 2 e 



To obtain the total e.rn.f. induced in the secondary, E' e must be 

 added to jraco/. Then 



If L e is negligible, the eddy current induces a component in 

 quadrature with that due to the primary current and of a mag- 



