Norton's theorem states that any two-terminal linear network can be replaced by an equivalent circuit consisting of a constant current source in parallel with an impedance. To determine the value of the parallel impedance, the source is replaced with its internal impedance. This resultant circuit's equivalent impedance is the Norton impedance, which is the same as the Thévenin impedance. To determine the Norton current, place the sources again in the circuit, and analyze the open-circuit voltage, which is the Thévenin voltage. The Thévenin voltage is determined by the product of the source current and the Thevenin impedance. The same voltage is dropped across the load impedance as it is placed in a parallel configuration. Recall the relationship between Norton current, Thévenin voltage, and Thévenin impedance. By substituting the values, it allows for the determination of the Norton current. Norton's theorem is beneficial for analyzing and designing systems containing complex AC circuits. By determining the Norton equivalent circuit for each stage or section of the complex circuit, the analysis of the overall system can be simplified.