INDUCTANCE AND CAPACITY 



405 



/1>M\ 7 , / IN 



(f ) R " = (f 



but 



1 JL = 1 JL _ i 



l r ' IT 



Substituting these values in (D) gives 



L x ~ 



1)+^]- 



(37) 



The Anderson bridge is now used with alternating currents 

 and a vibration galvanometer is employed as the detector. This 

 arrangement has been used at the Bureau of Standards, 21 Wash- 

 ington, in much of the recent and very accurate work on 

 measurements of inductance. 





kFiG. 236. Mesh diagram for Anderson bridge. 

 The necessary conditions for balance are shown below. 

 The impedances of the various branches are denoted by Z 

 with the proper subscript. The mesh equations are 



X(Z M + Z c ) - YZ -VZ C = 

 V(Z C + Z r + Z N ) - X(Z C + Z r ) - YZ r - I B Z N = 



Y(Z X + Z P + Z r + Z ) + X(Z X + Zp + Z r ) - VZ r - 



I B Z P = 0. 

 Solving for Y, the galvanometer current, 



IB\Z AfZcZp -j- Z \i 



_ 



denominator, a function of the impedances 

 .'. for balance, 



