The Balance Equation of an AC bridge

RBR1317

Joined Nov 13, 2010
713
assumption that the balance equation of the bridge is z1/z3=z2/z4
The balance equation is derived from there being two voltage dividers, each connected to opposite sides of the meter. Z1 & Z2 form one voltage divider, Z3 & Z4 form the other voltage divider. At the balance point (meter reads zero) both divided voltages are exactly equal. But in this problem, what would be the expression for Z3? I don't have a clue, but what I do have is the realization that at the balance point Vb=Ve (magnitude & phase). That is where I would start solving the problem.
 

MrAl

Joined Jun 17, 2014
11,389
is it ok to start solving this problem with assumption that the balance equation of the bridge is z1/z3=z2/z4

View attachment 124207

Hi,

Have you made any progress on this yet?
You should be able to get it down to two very short equations, one for L1 and one for R1.

My solutions forms hints are:
L1=C*(Ra*Rb+Rc*Rd+Re*Rf)
R1=Rg*Rh/Ri

but i wont give out the values of Ra through Ri just yet until you've shown some work. The idea in the homework section is always for the asker to post at least some attempt at an answer or at least explain why they cant do that. Also, some of the values above may be the same so that for example Ra may be equal to Re, or they may not be equal.
 
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