Find the node voltages of the circuit

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Homework Help Overview

The discussion revolves around finding the node voltages in an electrical circuit, specifically focusing on the application of node voltage analysis. The original poster presents a circuit diagram and mentions attempts to solve for voltages based on provided answers from a textbook.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need for setting up equations based on node analysis rather than drawing loops. There is mention of confusion regarding the correct setup of equations and the interpretation of the textbook answers. Questions arise about calculating net resistance and the applicability of series and parallel resistor formulas.

Discussion Status

Some participants have provided guidance on focusing on node analysis and calculating currents at specific nodes. There is acknowledgment of differing interpretations regarding the setup of the problem, and while some progress has been made, explicit consensus on the approach has not been reached.

Contextual Notes

Participants note the challenge of determining the correct equations and the ambiguity in the textbook answers regarding which voltages correspond to which nodes. There is also a hint provided for calculating net resistance that remains unclear to some participants.

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Homework Statement



[PLAIN]http://img339.imageshack.us/img339/6089/electriccircuits221revi.png

Homework Equations



i = v/R

The Attempt at a Solution



My attempt at the solution is all in the red in the diagram above. Apparently the book's answers are 1 V and 2 V and it doesn't say which voltage corresponds with what but I'll assume v1 = 1 V and v2 = 2 V. When I solved for v2 with my equation I got 20 V. Can someone help me out with getting the equations set up so I can solve for the voltages? I drew the loops I used in red. Since there's 2 unknowns, I need at least 2 equations. Problem is, I don't know if my equations are correct.
 
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You calculate the algebraic sum of currents at the nodes V1 and V2. There is no sense to draw the loops, note the currents in each branch connected to the nodes V1 and V2 instead.

ehild
 
Yeah someone pointed out to me I have to do node analysis. I ended up getting the book's answer for part a. How would I find the net resistance for part b? The hint is kind of confusing me.
 
Anyone got any sort of hint for part b? It doesn't look like i can use the formula's for resistors in series and parallel here the way the circuit is set up but I may be over thinking it.
 
Last edited:
The net resistance seen by the source is equal to the generator voltage divided by the generator current. Write the sum of currents at the node connected to the ground, and find the current flowing into the generator.

ehild
 

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