Help with Wheatstone bridge

WBahn

Joined Mar 31, 2012
30,058
You prove it by analyzing the circuit.

You need to show YOUR best attempt to work YOUR homework problem. That gives us a starting point from which to help you find where you are going astray.
 

Thread Starter

ronald1980

Joined Oct 29, 2016
6
Vrp = R ( 1+ ῥ) \ R + R ( 1+ ῥ)


Vrp = = R ( 1+ ῥ) \ R ( 1 + ( 1+ ῥ)


Vrp = v ({ 1+ ῥ) \ 2 + ῥ }


Vr = Vr\2r = 0.5R


Vrp – Vr = v ({ 1+ ῥ) \ 2 + ῥ } - 0.5VR

== > found the:

upload_2016-11-4_21-52-5.png


and from here i am stuck
 

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WBahn

Joined Mar 31, 2012
30,058
Vrp = R ( 1+ ῥ) \ R + R ( 1+ ῥ)
Look at your very first equation.

Presumably 'Vrp' is a voltage. Yet nothing on the right hand side is a voltage.

Then (and I'm having to guess) you have an order of operations error because you are dividing R ( 1+ ῥ) by R and then adding R ( 1+ ῥ) to the result.

If what you are trying to do is claim that the voltage across the Rp is obtainable by just throwing the voltage divider equation at V, R, and Rp, then you are mistaken because of the branch at the junction of R and Rp that goes out to Rf and R1.
 

WBahn

Joined Mar 31, 2012
30,058
I can not understand the circuit
Please Help ( i have a job interview)

thx
It sounds like you simply aren't ready for any job interview that would involve analyzing circuits like this.

Since you have the supposed answer (i.e., an expression for Vo as a function of V), first try verifying that the answer is correct by applying it to the problem and seeing if it really is the solution.

Once you have done that, then look at the circuit in light of the two key assumptions that are made regarding ideal opamps and then write down equations that reflect the application of those assumptions to this circuit. Just being able to articulate that will probably get you quite a bit of partial credit, per se, in an interview.
 

WBahn

Joined Mar 31, 2012
30,058
We don't just give out answers -- that doesn't do you any good. Make your best attempt to take what you've already been told and at least make a start so that we can see where you are going wrong next.
 
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