Possible Short Title: Possible Mistakes in Textbook Circuit Problems?

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In summary, the conversation discusses a problem with finding the current through an inductive element in a textbook, and the use of supermesh equations in solving the problem. One person points out an error in the supermesh equation and explains the correct way to write it. They also clarify the concept of supermesh and its relation to mesh analysis.
  • #1
Number2Pencil
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1

Homework Statement


The problem is attached. The question asks: "find the current through the inductive element". I'm starting to wonder how many mistakes are in this textbook. But it might be a mistake I made. Could someone check my Mesh Equations?


Homework Equations





The Attempt at a Solution



SuperMesh 1 & 2: 10V<0 + 1kohm(I1 + 6mA <0) + 4kohm (I2) + j6kohm (I2) = 0

SuperMesh Supplemental: I1 + I2 = 0.1 Vs

Direct Source Supplemental: Vs = (I1 + 6mA <0) * 1kohm

if anyone wants to take a stab at the final answer, I got 7.74mA <171.5, and the book got 1.378mA <-56.31. Way different than what I'm getting
 

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  • #2
Your supermesh equation is wrongly written.

Assuming that voltage gains are positive values, then in:
10V<0 + 1kohm(I1 + 6mA <0) + 4kohm (I2) + j6kohm (I2) = 0
the part "+ 4kohm (I2) + j6kohm (I2)" is incorrect as clearly there is a voltage drop (according to the direction of I2) across the 4k resistor and 6k inductor.

The correct supermesh equation should be:
10V<0 + 1kohm(I1 + 6mA <0) - 4kohm (I2) - j6kohm (I2) = 0
which should give you the desired answer.
 
  • #3
So in a supermesh, you treat it as going in one direction the entire way around? I was assuming you treated it as each direction showed

I was taught you add the voltage if there is a voltage drop (voltage drop in relation to the direction your reference mesh current), not subtract as you're showing. And if I'm wrong as you say, wouldn't the other part of the equation (involving the 1k resistor) be incorrect as well? I guess that would really depend on my first question as well
 
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  • #4
Number2Pencil said:
So in a supermesh, you treat it as going in one direction the entire way around?

Yes, because in mesh analysis you are actually applying the Kirchoff Voltage Law which equates all voltage drops (or equivalently voltage gains) around the loop to zero. And yes, you can only traverse the loop in either the clockwise or anticlockwise direction, not both. Supermesh is no different from mesh analysis except that you have now to consider more than one mesh current.
 
  • #5
thanks, I completely understand
 

Related to Possible Short Title: Possible Mistakes in Textbook Circuit Problems?

1. What is another circuit verification?

Another circuit verification refers to the process of double-checking a circuit design or simulation to ensure its accuracy and functionality before it is implemented in a physical form.

2. Why is another circuit verification important?

Another circuit verification is important because it helps to catch and fix any errors or potential issues in the circuit design, which can save time and resources in the long run and ensure the circuit works as intended.

3. What are the steps involved in another circuit verification?

The steps involved in another circuit verification typically include creating a simulation of the circuit, running tests and analyses on the simulation, identifying any errors or discrepancies, and making necessary adjustments to the design.

4. What tools are commonly used for another circuit verification?

Some commonly used tools for another circuit verification include simulation software such as SPICE, logic analyzers, oscilloscopes, and other test equipment.

5. How does another circuit verification differ from initial circuit verification?

Another circuit verification differs from initial circuit verification in that it is typically performed after the initial verification process to ensure the design is accurate and functional, whereas initial circuit verification is the first step in the design process to check for any major errors or issues.

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