1. Not finding help here? Sign up for a free 30min 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!

Diagonal resistance in circuit

  1. May 11, 2007 #1
    1. The problem statement, all variables and given/known data
    [​IMG]
    Find the equivalent resistance.

    2. Relevant equations
    equation for resistance. the variation used was 1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ...

    3. The attempt at a solution

    i have no idea how to add the diagonal in.
     
  2. jcsd
  3. May 11, 2007 #2

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Remember that you can stretch wires in any way you want to make the problem look simpler. Consider dragging the diagonal resistor, and the one to the right of it, to the right far enough that the diagonal resistor is no longer diagonal...

    - Warren
     
  4. May 11, 2007 #3
    short circuit
     
  5. May 11, 2007 #4

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    And yes, that's what comes next. :wink:

    - Warren
     
  6. May 11, 2007 #5
    oh, i see. but what do you mean by short circuit?

    [​IMG]

    edit: crap, i left something out. the problem was actually like the picture above. basically the same thing though.

    so could i redraw the picture as to simplify it like this:

    [​IMG]
     
    Last edited: May 11, 2007
  7. May 11, 2007 #6
    A short circuit is a condition whereby current passes through two nodes of a circuit (usually accidentally), without any resistance in between. Can you identify the short circuit in your circuit ?
     
  8. May 11, 2007 #7

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Consider this: if you put a piece of wire in parallel with a resistor, which path does the current take?

    - Warren
     
  9. May 11, 2007 #8
    the path of least resistance.
     
  10. May 11, 2007 #9
    so would that basically be a useless wire. in most situations anyway. but in the new diagram, there would be no short circuit.

    (oops. sorry bout the double post. i meant to edit.)
     
    Last edited: May 11, 2007
  11. May 11, 2007 #10

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Therefore... if you put a piece of wire in parallel with ANYTHING, the parallel combination acts just like a piece of wire by itself.

    - Warren
     
  12. May 11, 2007 #11
    Just to clear things up, if you have resistances in parallel, it doesn't essentially mean that the current passes only through the one with the least resistance, current gets divided in each of the branches, but the greatest current flows through the one with least resistance. In the case of short circuit in one of the branches (0 resistance) only, does all current pass through that particular 'piece of wire'.

    In your edited question, you don't require this concept, and the way you have redrawn the circuit appears correct.
     
  13. May 11, 2007 #12
    [​IMG]

    correct me if i'm wrong.

    the resistors in red are in parallel, so you can add them together with the equation of parallel resistance.

    then the resultant would be in series with the blue resistor, so you could simply add them together.

    now the resultant of that would be in parallel with the green resistor, so you can calculate their total with the equation again.

    then the resultant of that would be in series with the rest, so you could add them all together to find the total or equivalent resistance.

    yeah. i knew that current is divided up. i was had meant, the greater amount flows through the smaller resistor. nice catch, but as for you question. i don't know. would it.

    alright, thats good. thank you.
     
    Last edited: May 11, 2007
  14. May 11, 2007 #13

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You got it.

    - Warren
     
  15. May 11, 2007 #14
    yes. somewhat too late though. this had been a test question and i hadn't realized they are just wires.

    in case anybody needs it.

    [​IMG]
     
    Last edited: May 11, 2007
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Diagonal resistance in circuit
  1. Resistance In Circuits (Replies: 4)

  2. Circuit resistance (Replies: 4)

  3. Resistance circuit (Replies: 4)

Loading...