Which statement correctly describes the Norton equivalent in relation to Thevenin's theorem?

• A. A voltage source in series with a resistor
• B. A current source in parallel with a resistor
• C. A current source in parallel with a resistor; In = Voc / Rth; Rn = Rth
• D. A capacitor in parallel with a resistor

Answer: (C)

The key idea is that any linear network seen from two terminals can be represented in two interchangeable ways: Thevenin and Norton. The Norton form uses a current source in parallel with a resistor, and it behaves the same at the external terminals as the Thevenin form does.

In this Norton representation, the resistor value (the Norton resistance) matches the Thevenin resistance, since both come from the same network with sources turned off. The current source value is determined by how much current would flow if the output were shorted, which also relates to the open-circuit voltage and the Thevenin resistance: the Norton current equals the open-circuit voltage divided by the Thevenin resistance (In = Voc / Rth). This explains why the description of a current source in parallel with a resistor, with those relationships, is the correct characterization.

A capacitor in parallel is not the standard way to represent a general linear network in this context, and the Thevenin form (a voltage source in series with a resistor) is a different but equivalent representation, not the Norton form.