Kirchhoff's Laws help

  • Thread starter vaio911
  • Start date
  • #1
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Homework Statement



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


Homework Equations



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


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.
 

Answers and Replies

  • #2
6
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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.
 
  • #3
6
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It is because of the direction of the currents?
 
  • #4
CWatters
Science Advisor
Homework Helper
Gold Member
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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.
 

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