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Physics Olympiad question resistance and Electric circuit

  1. Nov 12, 2015 #1
    1. The problem statement, all variables and given/known data
    In the fig all resistors have resistance R. If pd of V is applied across AB.
    upload_2015-11-12_7-39-12.jpeg

    1)What is the outcome of joining C and D
    2)Whats is the pd across CO
    3)what is the resistance across A and B
    4)What is the resistance across AO
    2. Relevant equations
    V=IR
    1/∑R=1/R1 +1/R2

    3. The attempt at a solution
    So for
    1) i thought that it would cause a short circuit because instead of flowing through the resistors co &od it would directly flow.
    2)?
    3)?
    4)?
     
  2. jcsd
  3. Nov 12, 2015 #2

    mfb

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    Staff: Mentor

    What would flow from where to where? You are connecting C and D, not E and F.
     
  4. Nov 12, 2015 #3

    donpacino

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    what is the potential difference between C and D
     
  5. Nov 12, 2015 #4
    zero
     
  6. Nov 12, 2015 #5
    So i understand that between C and D no current flows. So there is ans for 2)no change right ?
     
  7. Nov 12, 2015 #6

    donpacino

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    yup :)
     
  8. Nov 12, 2015 #7
    so is the current direction i marked correct ? and does current flow from o to d or d to o ?
     
  9. Nov 12, 2015 #8

    donpacino

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    you wont know unless you know the resistor values... the real question, does the current direction you pick matter?
     
  10. Nov 13, 2015 #9

    mfb

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    Staff: Mentor

    As currents can be negative, you can draw the arrows in any direction you like. One direction will lead to positive current, one to negative current - unless the current is zero of course.
    Correct. How did you figure that out? A proper description will help with the next part.
     
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