How Do Thevenin's and Norton's Theorems Simplify Circuit Analysis?

[rgarforth]

Hi all, Hope everyone is fine and dandy!

I am having real problems with my homework, it is based on thevenins and nortons theorem. please see the attached word document for the questions.
I understand on the first question that the circuit is divided into two before calculating the voltage and resitances. please can you provide explanations with diagrams on how this is done.

Any Help much appreciated! Thankyou!

 

[Mindscrape]

What is your question?

For the first problem you would find the thevenin equivalent between A and B, so that when you change the load resistance the characteristics of the load will be easier to calculate.

For the second problem you merely use the norton equivalent so that you have a current source, and can calculate the current through the load easily.