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Determine the value of <math> I_x </math> using superposition.
 
Determine the value of <math> I_x </math> using superposition.
  
[[File:ECE201 P2.jpg|250px|center]]
+
[[File:ECE201 P2.jpg|300px|center]]
  
 
----
 
----
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Let's find <math> I_x </math> first by deactivating the voltage source as seen in the picture below.
 
Let's find <math> I_x </math> first by deactivating the voltage source as seen in the picture below.
[[File:ECE201_P3_2.jpg|175px|center]]
+
[[File:ECE201_P3_2.jpg|200px|center]]
 
We can find <math> I_x </math> by using loop analysis. The left loop can be <math> I_1 </math> and the right loop can be <math> I_2 </math>.<br />
 
We can find <math> I_x </math> by using loop analysis. The left loop can be <math> I_1 </math> and the right loop can be <math> I_2 </math>.<br />
 
When doing loop analysis we can come up with the following equation:<br />
 
When doing loop analysis we can come up with the following equation:<br />
 
<math>\begin{align}
 
<math>\begin{align}
I_1:\\
+
I_1:
 
     10*I_1 + 20(I_1 - I_2) = 0\\
 
     10*I_1 + 20(I_1 - I_2) = 0\\
 
       30*I_1 = 20*I_2\\
 
       30*I_1 = 20*I_2\\
I_2:\\
+
I_2:
 
     I_2 = 3A\\
 
     I_2 = 3A\\
 
\end{align}
 
\end{align}
</math>
+
</math><br />
  
After finding <math> I_1 </math> and <math> I_2 </math> we can find <math> I_x </math>.
+
After finding <math> I_1 </math> and <math> I_2 </math> we can find <math> I_x </math>.<br />
 
<math>\begin{align}
 
<math>\begin{align}
 
I_x = I_1 - I_2\\
 
I_x = I_1 - I_2\\
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Now we need to do the same procedure but this time we will deactivate the current source; therefore, we will get the following circuit:<br />
 
Now we need to do the same procedure but this time we will deactivate the current source; therefore, we will get the following circuit:<br />
[[File:ECE201_P3_3.jpg|175px|center]]
+
[[File:ECE201_P3_3.jpg|200px|center]]
  
 
We can use source transformation to turn the voltage source into the current then use current division to solve for <math> I_x </math>.<br />
 
We can use source transformation to turn the voltage source into the current then use current division to solve for <math> I_x </math>.<br />
 
After doing source transformation we get the following circuit:<br />
 
After doing source transformation we get the following circuit:<br />
[[File:ECE201_P3_4.jpg|175px|center]]
+
[[File:ECE201_P3_4.jpg|200px|center]]
  
 
Now use current division to find <math> I_x </math>.<br />
 
Now use current division to find <math> I_x </math>.<br />
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</math>
 
</math>
  
Finally, the last step would be to add up the two  <math> I_x </math><br /> we obtained by deactivating the voltage and current sources.
+
Finally, the last step would be to add up the two  <math> I_x </math> values we obtained by deactivating the voltage and current sources.
 
  <math> I_x = -1 + 2</math><br />
 
  <math> I_x = -1 + 2</math><br />
 
  <math> I_x = 1A</math><br />
 
  <math> I_x = 1A</math><br />

Latest revision as of 15:31, 2 May 2015


Superposition Practice

Practice question for ECE201: "Linear circuit analysis I"

By: Chinar Dhamija

Topic: Superposition



Question

Determine the value of $ I_x $ using superposition.

ECE201 P2.jpg


Answer

The circuit has two sources, a voltage and a current source. In order to find $ I_x $ we need to look at two instances.
1. Deactivate the voltage source (V = 0)
2. Deactivate the current source (I = 0)

Let's find $ I_x $ first by deactivating the voltage source as seen in the picture below.

ECE201 P3 2.jpg

We can find $ I_x $ by using loop analysis. The left loop can be $ I_1 $ and the right loop can be $ I_2 $.
When doing loop analysis we can come up with the following equation:
$ \begin{align} I_1: 10*I_1 + 20(I_1 - I_2) = 0\\ 30*I_1 = 20*I_2\\ I_2: I_2 = 3A\\ \end{align} $

After finding $ I_1 $ and $ I_2 $ we can find $ I_x $.
$ \begin{align} I_x = I_1 - I_2\\ I_x = 2 - 3\\ I_x = -1\\ \end{align} $

That is what we get for $ I_x $ if the voltage source is deactivated.

Now we need to do the same procedure but this time we will deactivate the current source; therefore, we will get the following circuit:

ECE201 P3 3.jpg

We can use source transformation to turn the voltage source into the current then use current division to solve for $ I_x $.
After doing source transformation we get the following circuit:

ECE201 P3 4.jpg

Now use current division to find $ I_x $.
$ \begin{align} I_x = \frac{1/10}{1/10 + 1/20} * 3\\ I_x = 2\\ \end{align} $

Finally, the last step would be to add up the two $ I_x $ values we obtained by deactivating the voltage and current sources.

$  I_x = -1 + 2 $
$ I_x = 1A $



Questions and comments

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