ELECTRICAL MEASUREMENT BY ALTERNATING CURRENTS 303 



Method 4- 



+ fl,,)] [# ( 

 R' R" 



Method 5. 



L, = [jy (r + R it ) + R"(R' 



A _ [fl, (^" 



c ' (R r + R") (R" + R 



Method 6. 



c O 



We can correct for self inductions, U, L" in the circuits R', R" by 

 using the exact equation 



R'R"(r+R")(R+R')=--0 

 or approximately 



= (R+B) (R'^--^- 



-. 

 + etc. 



Method 7. 

 R,R 3 M 13 M l2 + b*\_L 3 M l2 -MrM [^J/ M - Jf.JfJ = 



For a coil containing three twisted wires, M 12 = M 1S = M 23 and the 

 self inductions of the coils are also equal to each other and nearly equal 

 to the mutual inductions. Put an extra self induction L 3 in R 3 and a 



capacity C 2 in R 2 . Replace L 3 by L -f- L 3 and L 2 by L and we 



6 2 



can write 



As L M is very small and can be readily known, the formula will 

 give ^r When L M = we have 



Method 8. 



V M(M+ 1) = rR 2b* M* =~rR+(rR)' 



or V M(M L) = (rR)' 2b 2 LM rR (rR)' 



