# Confusion with Dependent V Source using Nodal and Loop analysis

Discussion in 'Homework Help' started by ohmagod, May 17, 2012.

1. ### ohmagod Thread Starter New Member

May 9, 2012
2
0
I have been studying for intro to circuit analysis midterm. I've come across two problems that I do not fully understand even though I have looked up the answers on Cramster.

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I approached this problem with loop analysis. First I related Io= I2-I3 , I3= -12mA , Ix= I1-I2 . I wrote out equations for the KVL around the L1( furthest left) and L2 (mid) . I ended up finding that I1=-9mA I2=-18mA. From this I found Io to be -6mA. When I looked up the answer it says that the Io= 0mA. Can you please tell me where I went wrong?

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The directions say to use nodal analysis, but I don't know how to deal with the current around the dependent voltage source. The solution posted was very unclear. I don't expect you to solve it for me, any guidance will help a lot.

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2. ### t_n_k AAC Fanatic!

Mar 6, 2009
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For the first problem the middle loop KVL equation would be

4000Ix=4000Ix-12000Io

which immediately implies that Io=0 with the Ix terms cancelling out.

3. ### ohmagod Thread Starter New Member

May 9, 2012
2
0
thank you for your help. My attempt was unnecessarily complicated. Anyone have any tips for the second one?

4. ### t_n_k AAC Fanatic!

Mar 6, 2009
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In the second problem there are two nodes.

The node voltage on the left is

$V_1=-4000I_x \ \ ...$$1$$$

At the right hand node - Vo node

$0.004=\frac{V_o}{10000} + I_x \ \ ...$$2$$$

Another equation is required for a solution

$V_o-V_1=10000I_x \ \ ...$$3$$$

Substitute equation (1) into (3) to eliminate V1 and simultaneously solve the result with equation (2) to find Vo