Norton’s theorem Statement: Any linear, active, resistive, network containing one or more voltage and / or current sources can be replaced by an equivalent circuit containing a current source called Norton’s equivalent current ISC and an equivalent resistance in parallel.
Superposition theorem Statement: Superposition theorem states that in any linear network containing two or more sources, the response (current) in any element is equal to the algebraic sum of the response (current) caused by individual sources acting alone, while the other sources are inoperative.