Calculating Thevenin Resistance - Load Removal & Voltage at Load Terminals

[esmeco]

I was wondering,how do we calculate the thevenin resistance in a circuit with a load resistor?Do we remove the load?How do we calculate the voltage Lat the load terminals.Like for example in this circuit:

http://i75.photobucket.com/albums/i281/esmeco/superpositionandthevenin.jpg

I'm a bit confused now...

 

[esmeco]

Can anyone help me?

 

[FrogPad]

What book are you using?

 

[esmeco]

Actually I'm not using a book...If you're referring to those exercises,they're practice exams...ANd for guidance I'm using a book in a language which isn't english...But I'm really confused because I've heard my colleagues saying that you don't necessarily remove the load resistor to find the thevenin at the load terminals,but on the Internet they all say you have to remove the load resistor inorder to find thevenin voltage...In this case,if we remove the load resistor I'm not sure on how we calculate the voltage at those terminals...

 

[FrogPad]

Go through the video examples on this website,
http://bcs.wiley.com/he-bcs/Books?action=resource&bcsId=2149&itemId=0471487287&resourceId=5675

I think it will help you out more.

As far as Thevinin's goes, you:

1) Remove the load.
2) Find the voltage across the terminals of the removed load V_{th}
3) Find the Thevenin equivalent resistance at those terminals R_{th}

If only independent sources,
short voltages
open currents

If only dependent or both dependendent and independent it differs.
I'll type up how to do it, if you need it.

4) Connect the removed load up to your new equivalent circuit,

Vth----Rth----(+)
|
|
|-------------(-)

Load connects to (+), and (-) terminal