1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Equivalent resistance across a circuit made of 12 resistors

  1. Sep 28, 2010 #1
    hey can anybody please tell me how to solve this circuit?? :confused:

    I tried this sum out but I can't understand which points are symmetrical and have same potential..or how the current is distributed

    Attached Files:

    Last edited: Sep 28, 2010
  2. jcsd
  3. Sep 28, 2010 #2
    The symmetry means that potential at C=D=E=F = 0.5 the pd between A and H
    This means there is no current through the arms CD and FG. So you can ignore the 2 resistors there.
    This allows you to simplify the circuit using series and parallel resistors.
  4. Sep 29, 2010 #3
    ok, I solved the combinations and I got 3/4 R.
    but what if the circuit is not symmetrical..that is if we have to find the equivalent resistance between A and B?
  5. Sep 29, 2010 #4
    I also get 3/4 R.
    If the circuit is not balanced, I can't see much use for it! Usually, these "bridge" type circuits are only useful when balanced. [eg Wheatstone bridge]

    To attempt to answer the question, though, one possibility would be to set up a system of Kirchhoff's Law equations for the various closed loops (where ΣIR = 0) as well as the main circuit supplying the pd that provides the main current.
    You would get 6 equations with 6 unknowns and a relationship between the main current and the applied pd. This would give the equivalent R.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook