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Find the value of Vout.
 
Find the value of Vout.
  
[[File:ECE201_P4_1.jpeg|400px|center]]
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[[File:ECE201_P2.jpg|500px|center]]
 
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[[File:ECE201_P4_2.png|20px|center]]
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===Answer ===
 
===Answer ===
In order to find Vs' we have the following equation:<br />
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The first step would be to solve for i using Ohm's Law.<br />
<math> 20 = Vs'a + 4b </math><br />
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<math> i = \frac{12}{4} </math><br />
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<math> i = 3A </math><br />
  
From the information present in the table two systems of equations can be created to solve for a and b.<br />
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We know that <math>V_+ = V_- </math>.<br />
First equation:<br />
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In order to find <math> V_+ </math> we need to use voltage division at the node connecting the 2 and 4 ohm resistor.<br />
<math> 10 = 4a + b </math><br />
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<math> V_+ = \frac{4}{4 + 2} * 9 </math><br />
Second equation:<br />
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<math> V_+ = 6 = V_- </math><br />
<math> 40 = 10a + 0b </math><br />
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After solving the above system of equations you get:<br />
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<math> a = 4 </math> and <math> b = -6 </math><br />
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Since we have both a and b values you can plug that into the Vs' equation and solve for Vs'.<br />
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Now that we know the voltage at the <math> V_- </math> node we can find Vout by using the following equation.<br />
 
<math>\begin{align}
 
<math>\begin{align}
20 = Vs'a + 4b\\
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i = \frac{V_- - Vout}{8}\\
20 = Vs'(4) + 4(-6)\\
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3 = \frac{6 - Vout}{8}\\
44 = 4Vs'\\
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24 = 6 - Vout\\
Vs' = 11 V
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Vout = -18 V\\
 
\end{align}
 
\end{align}
 
</math>
 
</math>

Latest revision as of 15:56, 2 May 2015


Op Amp Practice with Voltage Division

Practice question for ECE201: "Linear circuit analysis I"

By: Chinar Dhamija

Topic: Op Amp


Question

Find the value of Vout.

ECE201 P2.jpg


Answer

The first step would be to solve for i using Ohm's Law.
$ i = \frac{12}{4} $
$ i = 3A $

We know that $ V_+ = V_- $.
In order to find $ V_+ $ we need to use voltage division at the node connecting the 2 and 4 ohm resistor.
$ V_+ = \frac{4}{4 + 2} * 9 $
$ V_+ = 6 = V_- $

Now that we know the voltage at the $ V_- $ node we can find Vout by using the following equation.
$ \begin{align} i = \frac{V_- - Vout}{8}\\ 3 = \frac{6 - Vout}{8}\\ 24 = 6 - Vout\\ Vout = -18 V\\ \end{align} $


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