# Help with polarities

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#### devoured_elysium

Joined Jun 26, 2008
13
The second picture was made by me. The idea of the first and second pictures would be the two possible "interpretations" I could have done of the same problem. One with the current to one side, and another one to another. So the original picture is the first one, and the second one was MSPaint edited by me. But with all this mess, only now I realise something, which is, I think, what you mean: When making the second picture, I forgot to change the Va=2000 I1 to Va= - 2000 I2. Had I not made this mistake, and the result would be, since the beggining, the correct one, and I wouldn't even had to create this topic, as the method I am using seems to work for both ways, with this correction.

Btw, Thanks for your minuscious attention, otherwise I was about to giving it up! I cannot stress enough my appreciation for your help!

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#### studiot

Joined Nov 9, 2007
4,998
Well I'm glad we got that sorted.

If you can publish the rest of the circuit for other's benefit - it would be helpful.

This should include at least one more loop with a second diamond passing I2 and containing an arrow for direction.

cheers

#### JoeJester

Joined Apr 26, 2005
4,390
Working with just the first picture, the dependent source is 2000I1. If your stating the dependent source in the second pic as 2000I1, yet not displaying I1 anywhere, then the diagram is incomplete.

#### Ratch

Joined Mar 20, 2007
1,070
JoeJester,
I thought that I1 was a typo and he really meant 2000I. Ratch

#### studiot

Joined Nov 9, 2007
4,998
Va= - 2000 I2.
Note that the correct value is in terms of I2, which was not shown on the original diagram.

This is because the original diagram only showed half the circuit and half the symbol for a

current controlled dependent voltage source

The controlling current (I2) cannot, by definition, be in the same loop as the controlled voltage.
Equally the controlled voltage cannot, by both definition and common sense, be a function of the current (I1) passing through it.

So the original diagram was both wrongly labelled and incomplete hence my request for more information.

#### JoeJester

Joined Apr 26, 2005
4,390
Ratch,

The first diagram has I as I1, and the second diagram had I as I2. I too assumed he meant I, because he didn't include the I subscript in the text.

I could have misinterpeted it ... but I don't think so.

Attached is how I viewed the circuit.

Studiot ... I think it was more of an academic exercise vice practical, like modeling transistors, ops norm for homework.

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