Hello, I am asked to find the Norton equivalent of this circuit. So I did the calculations with source transformation. I did all the steps right but I am sort of confused on the last step to get the right answer. Initially I used the current division to find the Norton equivalent but it turns out I have already found it by the last source transformation. And I could easily find Rn by using the parallel formula. But I am confused on why I don't have to use current division to find the Norton equivalent in this case?
Best Answer
I'd say the simplest answer is because you've already found the Norton equivalent. You just used another technique to arrive at the answer.
A Norton equivalent circuit is just a current source and a shunt (parallel) resistor that has the same response as the original circuit. There are multiple ways to derive this. As you've demonstrated, it is possible to simply apply source transformations and combine resistances to reduce the whole circuit down to just a single current source and a single shunt resistor... which by definition is the Norton equivalent circuit.
It's also possible to analyze the circuit for \$V_{OC}\$ and \$I_{SC}\$ (and then derive \$I_N=I_{SC}\$ and \$R_N = V_{OC}/I_{SC}\$ ) without applying source transformations. If you take that approach, then you would need to perform current division. And you'd end up with the same answer. It's a good exercise to try out.