How Does Adding a Resistor Affect Thevenin Equivalents?

[LongApple]

Homework Statement

I'm having problems with PF's cut and paste images. They are not showing up on the actual webpage only on my editor.

See these:
http://i.imgur.com/mKfn27m.png
http://i.imgur.com/jCO2JRM.png
http://i.imgur.com/oUWFsuI.png

I created the above problem by modifying this problem on mitx:
http://i.imgur.com/PE0eSLC.png <--(I don't care about the solution for this, I care about the solution for the question I wrote above)

Quesiton A - What current is this? THe one going through R2
Question B- is V_th = capital i * R2?
The last question, Question C is "does R3 contribute anything now?"

I created this problem though it is loosely based on the original problem on mitx's website except I have added one resistor at R3

Homework Equations

V=IR I bet.

The Attempt at a Solution

See above pisI created this problem though it is loosely based on the original problem on mitx's website except I have added one resistor

 

[LongApple]

Delete accidental post (there were problems with the image pasting on PF). Ultimately, I've decided to use imgur instead because it is not giving me the same problems as PF's image copy and paste.

 

[LongApple]

Delete accidental post

 

[gneill]

Delete accidental post (there were problems with the image pasting on PF). Ultimately, I've decided to use imgur instead because it is not giving me the same problems as PF's image copy and paste.

Just upload your images. Hit the "UPLOAD A FILE" button.

 

[gneill]

With regard to your question, the added resistor does not effect the circuit at all. A branch with a current source will pump out the same current regardless of what the current source is in series with. And an open circuit (the hanging resistor) does nothing if no current can flow through it.

 

[LongApple]

With regard to your question, the added resistor does not effect the circuit at all. A branch with a current source will pump out the same current regardless of what the current source is in series with. And an open circuit (the hanging resistor) does nothing if no current can flow through it.

V_TH=R2?
and VTH=R2?

Somehow that does not sit well in my mind. What is R3 was ten billion ohms? Shouldn't that do something?

 

[gneill]

V_TH=R2?
and VTH=R2?

I'm not sure what you mean here. A resistance is not a voltage.

But with or without your new resistor, the circuits will behave identically (from the point of view of the load) and will have the same Thevenin or Norton equivalents.

Somehow that does not sit well in my mind. What is R3 was ten billion ohms? Shouldn't that do something?

Well, it'll generate a LOT of heat with the current that flows through it.

Remember, an ideal current source will produce ANY voltage required to maintain its specified current. So no matter how much voltage is dropped across a resistor that's in series with it, you'll still get the same current coming out of the combination.