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!

Kirchhoff's Laws help

  1. Sep 25, 2013 #1
    1. The problem statement, all variables and given/known data

    Find [itex]i_1,i_2,v_A,\text{ and }v_H[/itex] in the ladder network. Calculate the power dissipated in the [itex]2\;\Omega[/itex] resistor.

    http://i.snag.gy/PIhxl.jpg


    2. Relevant equations

    Kirchhoff's Laws (i.e. current law, voltage law).


    3. The attempt at a solution

    Ok, I know that I can simplify the circuit down to one loop then use Ohm's law to calculate [itex]i_1[/itex], but then I have to do other things to get the other stuff.

    I tried to make a system to solve this problem using the laws.
    Can somebody tell me where I'm doing wrong here?

    [itex]
    \begin{align}
    i_b&=i_c+i_a\\
    i_c&=i_e+i_d\\
    i_e&=i_g+i_f\\
    12i_a-28+8i_b&=0\\
    12i_a+6i_c+15i_d&=0\\
    4i_e+10i_f+15i_d&=0\\
    2i_g+13i_h+10i_f&=0\\
    4i_e+2i_g+13i_h+15i_d&=0
    \end{align}[/itex]

    Getting me something like:
    [itex]-\frac{7}{39},\frac{49}{13},\frac{154}{39},\dots[/itex]

    which I know is completely off.
     
  2. jcsd
  3. Sep 25, 2013 #2
    If you can't understand my handwriting,

    [itex]V_a[/itex] is the one w/ the 12 ohms.

    [itex]V_h[/itex] is the 13 ohms one.
     
  4. Sep 25, 2013 #3
    It is because of the direction of the currents?
     
  5. Sep 26, 2013 #4

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    I'd probably just simplify it. If you keep your working for each step it will help when it comes to working out the voltages using the potential divider rule.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted