Fairly simple Op Amp diagram, help please!

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Homework Statement



A picture of the original problem can be seen http://images3a.snapfish.com/232323232fp733<2>nu=52::>379>256>WSNRCG=335;;84268347nu0mrj" along with some extra labels.

Homework Equations



superposition

The Attempt at a Solution



So I tried to solve A) with superposition, but first we know that:

[tex] V_{0}=V_{0_{1}}+V_{0_{2}} [/tex]

[tex] V_{1}=V_{2} [/tex]

and

[tex] i_{V_{1}}=i_{V_{2}}=0 [/tex]

just meaning there is no current going into the op amp.

Superposition: 4v source off with a short circuit in its place. We now have a current-to-voltage converter which follows this formula:

[tex] \frac {V_{0_{1}}}{i_{s}}=-R [/tex]

[tex] \frac {V_{0_{1}}}{.001a}=-2000\Omega [/tex]

[tex] V_{0_{1}}=-2V [/tex]

Now turn the current supply off and you have a non-inverting amplifier circuit with negative feedback. I am not really sure how to calculate this. To me it looks like:

[tex] V_{0_{2}}=V_{in}=4v [/tex]

and putting it together:

[tex] V_{0}=-2v+4v=2v [/tex]

which is the correct answer but I have no idea if I did it correctly or not. I do not know how to work out B but maybe if I get help here I will understand. Thanks!
 
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