How to Determine the Resistance R1 in a Mixed Circuit Analysis?

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Homework Help Overview

The discussion revolves around determining the resistance R1 in a mixed circuit analysis involving various resistors, voltages, and currents. Participants are examining the relationships between these elements using circuit laws.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants are attempting to use Ohm's law and Kirchhoff's laws to derive values for the unknowns in the circuit. There is a focus on the relationship between R1 and the known values of other components. Questions arise about the completeness of the provided information and whether algebraic expressions are acceptable.

Discussion Status

The discussion is active, with participants exploring different interpretations of the circuit setup. Some have suggested potential equations to express the relationship between the voltage source and the resistors, while others are questioning the adequacy of the information provided to derive numerical values.

Contextual Notes

There is a noted lack of complete problem statements, and participants are clarifying the requirements for the solution, including whether numerical values or algebraic expressions are needed.

Logan Batson
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Homework Statement



The following circuit is given, and all voltage, current, resistance and power must be found for each resistor.

EsxxS0K.jpg


I have found the following information:

Vsrc = ?
Isrc = .5A
Rsrc = ?
Psrc = ?

V1 = ?
I1 = .5A
R1 = ?
P1 = ?

V2 = 2.5V
I2 = .25A
R2 = 10
P2 = .625W

V3 = 2.5V
I3 = .25A
R3 = 10
P3 = .625W

V4 = 5V
I4 = .25A
R4 = 20
P4 = 1.125W

How would I solve for the information of R1?

Homework Equations



V = IR

The Attempt at a Solution



I originally had thought that V1 is 5V, as the current is the same as the simplified parallel section. If the voltage from the cells is constant, and half of the circuit uses 5V, then I had assumed the other section would use 5V as well, as both currents are the same.
 

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Logan Batson said:

Homework Statement



The following circuit is given, and all voltage, current, resistance and power must be found for each resistor.

View attachment 235274

I have found the following information:
That makes it obvious that you have not provided a complete problem statement. WHERE have you "found" this information?
 
phinds said:
That makes it obvious that you have not provided a complete problem statement. WHERE have you "found" this information?

The information given with the circuit is:

I1 = 0.5A
V3 = 2.5V
V4 = 5V
P3 = 0.625W

Sorry about not including this. Using Ohm's law, Kirchhoff's laws, and the equation P = VI, I had determined all other variables of the circuit using this information.
 
OK, so the circuit simplifies to R1 in series with a 10 ohm resistor that has 1/2 amp flowing through it and 5 volts across it. I don't see how this is enough information to tell anything about R1 and the voltage source --- they have a relationship, but you can't get numerical values. Are you sure this is all the info you were given?

EDIT: Oh, wait ... is it a requirement to get numerical values or is an algebraic expression OK?
 
phinds said:
OK, so the circuit simplifies to R1 in series with a 10 ohm resistor that has 1/2 amp flowing through it and 5 volts across it. I don't see how this is enough information to tell anything about R1 and the voltage source --- they have a relationship, but you can't get numerical values. Are you sure this is all the info you were given?

EDIT: Oh, wait ... is it a requirement to get numerical values or is an algebraic expression OK?

An equation would work too! Thanks for helping
 
Logan Batson said:
An equation would work too! Thanks for helping
OK. Can you get the equation? It should be really simple since you've got a simplified circuit that is two resistors and a power supply
 
phinds said:
OK. Can you get the equation? It should be really simple since you've got a simplified circuit that is two resistors and a power supply

It should just be (Vt - 5) = 0.5(Rt - 10) right?
 
Logan Batson said:
It should just be (Vt - 5) = 0.5(Rt - 10) right?
No, I think you are counting the equivalent resistor twice.

I get V - 5 = .5R1
 
phinds said:
No, I think you are counting the equivalent resistor twice.

I get V - 5 = .5R1

Oh okay, I understand now. Thanks so much for your help
 

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