Electric Circuts (Voltage, Ohms, Amps)

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Homework Help Overview

The discussion revolves around an electric circuits problem involving voltage, resistance, and current, specifically focusing on the relationship between resistors R3 and R4 in a circuit configuration. Participants are attempting to clarify their calculations and assumptions regarding the circuit setup.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are discussing the implications of not having a value for R3, with some suggesting that the problem can only be expressed in terms of R3 as a variable. Others are questioning the assumption that R3 and R4 are in parallel, clarifying that they are actually in series. There are attempts to derive voltages based on known values and current through the circuit.

Discussion Status

There is ongoing exploration of the problem, with some participants providing guidance on how to approach the calculations based on the known voltage and current. Multiple interpretations of the circuit configuration are being discussed, and while some participants express confusion, others are attempting to clarify the relationships between the components.

Contextual Notes

Participants note the absence of a specific value for R3 as a significant constraint, which affects the ability to solve the problem directly. The discussion includes references to Ohm's Law and the need to understand the circuit's configuration better.

Kmcquiggan
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Homework Statement
Examine circuit and complete table and determine the power of the circuit.
Relevant Equations
v_1= I_1 R_1,I_3=I_4= I_T-I_2,R_T= V_T/I_T
246044


I made a chart and this is my attempt. I am not sure that I am doing the calculations right thou

246045
 
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(1) Since there is no value for r3, the problem is unsolvable except as equations using r3 as the independent variable
(2) Show your work (I'm assuming YOU have a value for r3)
 
No there is no value for R3
 
Kmcquiggan said:
No there is no value for R3
Then your answers are all bogus.
 
I was assuming because R3 and R4 are parallel that the values would be the same.
 
Kmcquiggan said:
I was assuming because R3 and R4 are parallel that the values would be the same.
r3 and r4 are NOT in parallel, they are in series and there is zero reason to assume they have the same value whether they are series or parallel.
 
Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find
 
Kmcquiggan said:
Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find
As I have already said, it IS solvable, it's just that the answers will be equations using r3 as the independent variable
 
Kmcquiggan said:
Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find
You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.
 
  • #10
ehild said:
You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.
Good catch. I didn't even see the amperage figures. o:)
 
  • #11
phinds said:
Good catch. I didn't even see the amperage figures. o:)
I was wondering!
OP: I believe you did everything correct except your assumption about R3 and therefore the voltage across it. Did you do the table like "cross word puzzle" or did you write down equations?. Either way is fine but learn to do both!
 
  • #12
I wrote down the equations and did them one by one on a scrap piece of paper. And thank you for the help :)
 
  • #13
ehild said:
You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.
I am lost on how to find this. I was multiplying the resistance by the current? I am assuming that is not the formula
 
  • #14
Kmcquiggan said:
I am lost on how to find this. I was multiplying the resistance by the current? I am assuming that is not the formula
Why not?
Do you know Ohm's Law? The current through R4 is 0.06 A, The resistance R4 is 12 ohm. So what is the voltage across R4?
 

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