NORTON THEOREM
Norton theorem bears a close resemblance to Thevenin’s theorem.
The Norton equivalent of a linear network is the Norton current source isc in parallel with the Thevenin resistance Rth. Thus, we see that in fact it is possible to obtain the Norton equivalent of a network by performing a source transformation on the Thevenin equivalent. This result in a direct relationship between Voc, isc and Rth.
Voc =Rthisc