Find the Voltage in the following circuit diagram

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Discussion Overview

The discussion revolves around finding the voltage \( V_x \) in a given circuit diagram, focusing on the application of circuit analysis techniques. Participants engage in problem-solving related to circuit equations and the behavior of components within the circuit.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents an initial approach to the problem, using Kirchhoff's voltage law to set up the equation \( V_x + V_1 - 15 + V_2 + 2V_x = 0 \), leading to \( 3V_x + V_1 + V_2 = 15 \), but expresses uncertainty about the necessity of \( V_1 \) and \( V_2 \) without current information.
  • Another participant questions the initial equations and suggests re-evaluating the loop equation, implying that there is a current that influences the voltage drops.
  • A later reply proposes a calculation involving current \( i \) and derives \( i = \frac{15}{18} = \frac{5}{6} \; A \), leading to a voltage calculation of \( V = I \cdot R = \frac{5}{6} \cdot 5 = \frac{25}{6} \; V \).
  • One participant seeks clarification on whether the current is the same throughout a series circuit, indicating a conceptual understanding of series circuits.
  • Another participant expresses uncertainty about the nature of the voltage controlled current source, suggesting it might actually be a current source or a voltage controlled voltage source (VCVS), indicating a potential misunderstanding of circuit components.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the controlled source in the circuit, with some asserting it is a voltage controlled current source while others suggest it may be a current source or a VCVS. The discussion remains unresolved regarding the correct identification of the source and the necessity of certain voltage labels.

Contextual Notes

Participants note the absence of current information in the circuit, which complicates the analysis. There is also ambiguity regarding the definitions and roles of the components involved, particularly the controlled source.

vaio911
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Homework Statement



Find V_x in the circuit.

CFDeZ.jpg

Homework Equations



\displaystyle{\sum V_i=0}

The Attempt at a Solution



I tried to add all of the voltages and label the 2 ohm res V1 and 1 ohm res V2.

Then I did:

V_x+V_1-15+V_2+2V_x=0

3V_x+V_1+V_2=15

but then I couldn't find any other equations that will aid me in solving this.
I'm not really sure if I really need the V1 and V2.
The circuit doesn't give you the current either, so I don't know why resistance would help.

Thanks.
 
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vaio911 said:

Homework Statement



Find V_x in the circuit.

CFDeZ.jpg



Homework Equations



\displaystyle{\sum V_i=0}



The Attempt at a Solution



I tried to add all of the voltages and label the 2 ohm res V1 and 1 ohm res V2.

Then I did:

V_x+V_1-15+V_2+2V_x=0

3V_x+V_1+V_2=15

but then I couldn't find any other equations that will aid me in solving this.
I'm not really sure if I really need the V1 and V2.
The circuit doesn't give you the current either, so I don't know why resistance would help.

Thanks.

Welcome to the PF.

Where did you come up with those equations? There is one current around that loop that generates the voltage drops and controls the voltage controlled current source. Could you please try writing the one equation for the loop again, and solving it?
 
reply

Is this right?

i is the current

\begin{align*}<br /> 2V_x+V_x+2i+i&amp;=15\\<br /> 3(5\cdot i)+2i+i&amp;=15\\<br /> i&amp;=\frac{15}{18}=\frac{5}{6}\;A<br /> \end{align*}

V=I\cdot R=\frac56 \cdot 5=\boxed{\dfrac{25}{6}\;V}
 
Also, current is the same throughout in a series circuit right/
 
vaio911 said:
Is this right?

i is the current

\begin{align*}<br /> 2V_x+V_x+2i+i&amp;=15\\<br /> 3(5\cdot i)+2i+i&amp;=15\\<br /> i&amp;=\frac{15}{18}=\frac{5}{6}\;A<br /> \end{align*}

V=I\cdot R=\frac56 \cdot 5=\boxed{\dfrac{25}{6}\;V}

The diamond source is a voltage controlled current source, right? Not a voltage...

vaio911 said:
Also, current is the same throughout in a series circuit right/

Correct.
 
Upon further review, and input from another Mentor, I may be wrong about the controlled source. It looks like a current source to me, but I could be wrong about that. It may be a voltage controlled voltage source (VCVS) instead. Sorry if I mislead you on this.
 

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