Kirchhoff's law: Find the current I3 through the Amp meter

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Homework Help Overview

The discussion revolves around applying Kirchhoff's laws to a circuit analysis problem, specifically focusing on finding the current I3 through an ammeter. Participants are analyzing the relationships between currents I1, I2, and I3 in the context of two loops in the circuit.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants describe their attempts to formulate equations for the upper and lower loops of the circuit. There are discussions about the correctness of the equations and the incorporation of resistors. Some participants question the accuracy of their results and the application of Kirchhoff's Voltage Law.

Discussion Status

There is ongoing verification of the equations and results presented by participants. Some have expressed confidence in their calculations, while others are seeking confirmation of their reasoning and results. The discussion reflects a mix of agreement on certain calculations and uncertainty about the implications of the results.

Contextual Notes

Participants note potential inaccuracies in their calculations and the need for more precise values, particularly regarding the rounding of current values. There is an emphasis on ensuring that Kirchhoff's laws are satisfied in the context of the circuit analysis.

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Homework Statement
Find the current I3,I2, and I1 through the Amp meter.
Answer in units of A.
Relevant Equations
I used the Junction Rule - I3= I1+I2
I separated the circuit into parts- upper and lower

For the upper loop I wrote: -14-2I1-3.4I3-I2 = 0
For the lower loop I wrote 16-2.9I2+3.4I3-5.4I2 = 0

I solved for I1 and I2 separately and plugged it into the junction rule and solved for I3.

I may have got it wrong because of the incorporation of the extra resistor in the upper loop and lower loop and solved incorrectly.

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Correction for the problem after i found I3 correctly now.

The correct equation is now -14+3.3(I1)+3.4(I3)+2(I1)= 0 for the upper loop and
-16+5.3(I2)-3.4(I3)+2.9(I2) = 0 for the bottom loop. Once you separate variables, I2 = stuff and I1 = stuff, you can use the junction rule I1 = I2+I3 and rearrange to get I1-I2=I3. Plug it in and you should get I3 = 0.336A
 
Use I3 to get I2 and I1 since you have separate equations for them already -

I1 = -3.4(I3)+14/5.3 and I2 = 3.4(I3) +16/ 8.2

I1 = 2.43 A , I2 = 2.09 A
 
If anyone else sees this, can you verify that my explanation is correct since I was able to get the correct answers on my own.
 
## \text { The explanation is correct, but the result can be more accurate. } ##

## 3,3 \Omega \cdot 2,43 A + ( - 14 ) V + 2 \Omega \cdot 2,43 A + 3,4 \Omega \cdot 0,336 A = ##
## = 8,0058 V – 14 V + 4,852 V + 1,1424 V = ##
## = 0,0214 V \neq 0 V ##
## \text { It is hard to say that Kirchhoff Voltage Law is satisfied for the upper loop because it is hard to say that } 0,0214 V \text { is equal to } 0 V \text { . } ##
## \text { The more accurate result can be got rounding the value of } I _ 1 \text { to } 2,426 A \text { instead of } 2,43 A \text { . } ##
## \text { Values of } I _ 2 \text { , which is } 2,090 A \text { , and } I _ 3 \text { , which is } 0,336 A \text { , can remain the same. } ##
 

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