Find Current I3 in Circuit - Homework Statement

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Homework Help Overview

The problem involves finding the current I3 in a circuit, with participants discussing the relationships between various currents and resistances in the circuit configuration.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between currents I1, I2, and I0, questioning the assumptions about voltage across resistors R1, R2, R3, and R4. There is an attempt to set up equations based on these relationships, but some participants express uncertainty about their reasoning.

Discussion Status

The discussion is ongoing, with participants sharing their attempts and questioning each other's reasoning. Some guidance is offered, but there is no clear consensus on the correct approach or solution yet.

Contextual Notes

Participants note potential errors in their calculations and assumptions about the circuit, indicating a need for clarification on the relationships between the currents and resistances involved.

Gauss M.D.
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Homework Statement



Find the current marked I3 in the circuit.

Homework Equations





The Attempt at a Solution



The voltage over R2 and R1 is the same. The current I0 (12mA) is the sum of I2 and I1.

I1*R1 = I2*R2:
4*I1 = 1.25*I2

I1 + I2 = 12 <=> I2 = 12 - I1

4*I1 = 1.25*(12 - I1) = 15 - 1.25I1
5.25*I1 = 15

I1 = 2.86

I think I've messed up already here. Can anyone spot what I'm doing wrong??
 

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Gauss M.D. said:

Homework Statement



Find the current marked I3 in the circuit.

Homework Equations





The Attempt at a Solution



The voltage over R2 and R1 is the same. The current I0 (12mA) is the sum of I2 and I1.

I1*R1 = I2*R2:
4*I1 = 1.25*I2

It is wrong. The voltage over R3 and R4 is the same .

Gauss M.D. said:
I1 + I2 = 12 <=> I2 = 12 - I1

4*I1 = 1.25*(12 - I1) = 15 - 1.25I1
5.25*I1 = 15

I1 = 2.86

I think I've messed up already here. Can anyone spot what I'm doing wrong??
 
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Likes   Reactions: 1 person
Thanks! Is I2 still the sum of I3+I4 though? :S
 
Gauss M.D. said:
Thanks! Is I2 still the sum of I3+I4 though? :S

Sure.
 

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