Basic Electric Circuit: Find v1 & v2

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Discussion Overview

The discussion revolves around solving a homework problem related to an electric circuit, specifically finding the voltages v1 and v2. The participants explore various approaches to apply circuit laws and concepts to arrive at the solution.

Discussion Character

  • Homework-related, Technical explanation, Mathematical reasoning

Main Points Raised

  • One participant attempts to use Kirchhoff's Voltage Law (KVL) to derive an expression for v1 and questions the current flow through certain resistors.
  • Another participant suggests using the concept of a potential divider and notes that the current through the 3Ω resistor is zero, prompting an application of Kirchhoff's Current Law (KCL).
  • A participant reiterates the idea of treating the 3A current source in conjunction with the 2Ω resistor and discusses the implications for current through other resistors.
  • One participant claims to have solved the problem, stating that v1 = 14V and v2 = 6V, which they believe to be correct.
  • A later reply confirms the values of v1 and v2 as correct.

Areas of Agreement / Disagreement

While there is a progression towards a solution, the discussion includes multiple approaches and interpretations of circuit laws. Some participants propose different methods and reasoning, indicating that there is no single agreed-upon method until the final values are confirmed.

Contextual Notes

Participants express uncertainty about the current flow through specific resistors and the treatment of the current source, indicating that assumptions about the circuit configuration may influence their reasoning.

Who May Find This Useful

Students or individuals interested in learning about circuit analysis, particularly those seeking assistance with applying KVL and KCL in electric circuits.

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Homework Statement


Consider the circuit shown. Find the values of v1 and v2.

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Homework Equations

The Attempt at a Solution


I tried using KVL on the left closed loop and got:
$$v_{1} = 30 - 8i$$
I then used the current law between the two loops to get:
$$ i_{1} - v_{1} / 7 = v_{2} / 2 - 3$$
That's where I'm stuck. Do the two resistors next to a and b have any current flowing through them? Would it also be possible to treat the 3A current source as a resistor and combine it with the ##2\Omega## resistor it's in parallel with? Thanks.
 
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Perhaps try another approach. Are you familiar with the concept of a potential divider ?

If not then note that the current through the 3Ohm is zero and apply KCL to the node on the left of the 3Ohm. What does it tell you about the current through the 8 and 7 Ohm?

The current through the 4 Ohm is also zero.
 
Would it also be possible to treat the 3A current source as a resistor and combine it with the 2Ω 2\Omega resistor it's in parallel with?

Note the current through the 4Ohm is zero. Apply KCL to the node on the right of the 4Ohm. What does that say about the current through the 2 OHM?
 
CWatters said:
Perhaps try another approach. Are you familiar with the concept of a potential divider ?

If not then note that the current through the 3Ohm is zero and apply KCL to the node on the left of the 3Ohm. What does it tell you about the current through the 8 and 7 Ohm?

The current through the 4 Ohm is also zero.
So the current for both the 8 ohm and 7 ohm resistor would be ##i_{1}## and the current through the 2 ohm resistor would be 3 A. I can see how to solve it now. I'm getting v1 = 14 and v2 = 6, which looks correct.

Thanks for the help.
 
Yes v1=14V and V2 =6V is correct.
 

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