﻿of a Balanced Alternating- Current Bridge. 1025 



desired quantities can be readily deduced. While his 

 results will be very valuable to the practical users of tbe 

 bridge, the other side of the problem, that is, a generali- 

 zation of the theory, may prove to be of interest to 

 investigators of new possibilities of bridge connexions. 



Fig. 1 represents general connexions of an a.c. bridge, 

 with an impedance in each branch, and a mutual inductance 

 in each of the lower branches. The upper left-hand branch 

 consists of two paths in parallel, and the galvanometer is 

 connected at an intermediate point, A 2 ', of one of the paths. 



>0 



FLr. 1. 



lu-l 



' Ai /£ 



■^vvww^wv 



Galvanometer 

 or 



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Telephone 



i a 



•vwv^vwv-- 



i„-hi, 



^fflZ M > JV&i^ 3 



A.C. Source 



This is the arrangement used in the so-called Anderson 

 bridge, and is included in the general scheme because of its 

 further possibilities. The bridge is supposed to be balanced 

 on alternating current, that is, the galvanometer current is 

 supposed to be equal to zero. 



The current in the lower branches is denoted by Ij, that in 

 the upper branches by I u . In the divided branch 2 the 

 current through the lower path is denoted by I, so that the 

 current through the other path is I M — I. The line current is 

 lu + li. The impedances Z in the two left-hand branches are 

 denoted with the subscripts 1 and 2, to agree with the 

 sketches in Dr. Poole's article. The right-hand quantities 

 are provided with the subscripts 3 and 4, although Dr. Poole 

 uses again the subscripts 1 and 2, except in his fig. 5, where 

 the subscript 4 is introduced in the same place as in this 

 article. 



