Is there a different arrangement to measure resistance using Wheatstone bridge?

Discussion in 'General Electronics Chat' started by Devika B S, Sep 6, 2017.

  1. Devika B S

    Thread Starter Member

    Mar 8, 2017
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    20170906_215723.jpg

    The first circuit (A) is the one given in my textbooks and also the one used in labs to measure resistance using Wheatstone bridge. I know how this works and all the derivations associated with it.
    But recently, I came across some other worksheet materials with circuit (B) in which the way the readings are taken differs. The galvanometer is connected across different resistances compared to A. Wouldn't all the equations change for this arrangement? It appears to me that it's connected in the wrong manner.
     
  2. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    Diagram B is connected incorrectly. The galvanometer will simply read the supply voltage and be completely unaffected by changes in any of the four resistors.
     
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  3. WBahn

    Moderator

    Mar 31, 2012
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    Look carefully at the worksheet with circuit (B). One of the following possibilities likely applies:

    1) You read it incorrectly.
    2) It is part of a trick question or demo of how not to do things.
    3) It is an artwork error -- the text around the figure may give a hint that this is the case.
    4) Whoever wrote it should have been shot as a small child.
     
  4. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    4) Is a bit drastic. Perhaps given alternative employment?
     
  5. Devika B S

    Thread Starter Member

    Mar 8, 2017
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    Probably, its option 2 as I remember a teacher giving a worksheet with voltmeter connected in series with the resistor to be measured (instead of placing it across the resistor) and then saying its wrong. And a question in a workbook where its impossible to find the Thevenin's equivalent with the explanation saying that its not possible to find the Thevenin's equivalent for that circuit.
     
  6. WBahn

    Moderator

    Mar 31, 2012
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    But effective, although a time machine is required to implement the strategy. :D
     
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