Solving Basic Circuit Problem: Find Voltage Across 10 Ohm Resistor

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Discussion Overview

The discussion revolves around solving a circuit problem to find the voltage across a 10 ohm resistor. It includes aspects of circuit analysis methods and the application of Ohm's law, with participants exploring various approaches to the problem.

Discussion Character

  • Homework-related, Technical explanation, Debate/contested

Main Points Raised

  • One participant attempts to solve the problem using Ohm's law but expresses uncertainty about their calculations and arrives at a different answer than expected.
  • Another participant points out that the 30 and 60 ohm resistors are not in parallel due to the voltage source, suggesting the need for a more comprehensive circuit analysis method.
  • Some participants mention source transformation as a method used in the book's solution, which they believe is not appropriate for the problem's context.
  • There is a discussion about the applicability of nodal analysis and mesh analysis, with some participants expressing a desire to solve the problem without these methods.
  • One participant acknowledges the need for more than simple resistor network reductions and suggests that nodal analysis would be a suitable approach.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method to solve the problem, with multiple competing views on the appropriateness of different circuit analysis techniques and the use of source transformation.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about circuit configurations and the methods available to the participants. The discussion does not resolve the mathematical steps or the validity of the proposed approaches.

Magnawolf
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Homework Statement



ioM3d59.png


Find voltage across 10 ohm resistor.

Homework Equations



Ohm's law

The Attempt at a Solution



20 // 30 = 12
30 // 60 = 20

That's as far as I can get. The answer is 14.286.
 
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While the 20 and 30 Ohm resistors are in parallel, the 30 and 60 Ohm resistors are not (the voltage source intervenes).

You'll need to pull out some circuit analysis method. There are several choices. What methods have you studied so far?
 
jvbP2jN.png


Here's the solution to the problem.

It looks like the book did source transformation, which I didn't think was fair because this problem is before source transformation.

I know nodal analysis and mesh but I thought it was possible to do without them. I thought you could just find the R-total and then you could find the total current. I guess not?
 
Magnawolf said:
jvbP2jN.png


Here's the solution to the problem.

It looks like the book did source transformation, which I didn't think was fair because this problem is before source transformation.
Yup, they did a source transformation (Norton) and then current division.

I know nodal analysis and mesh but I thought it was possible to do without them. I thought you could just find the R-total and then you could find the total current. I guess not?
You need more than simple resistor network reductions (parallel/serial) here. Nodal analysis would be a good choice.
 
alright thanks
 

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