Which statement correctly describes the Norton equivalent?

• A. The Norton equivalent consists of a current source in parallel with a resistor.
• B. The Norton equivalent is a voltage source in series with a resistor.
• C. The Norton equivalent is a current source in series with a capacitor.
• D. The Norton equivalent is a voltage source in parallel with an inductor.

Answer: (A)

The idea behind the Norton equivalent is to replace a network with a current source in parallel with a resistor. This form captures the same behavior at the output terminals for any load: the current source provides a fixed current, and the parallel resistor models the network’s effective resistance, so the terminal current and voltage follow the same I–V relation as the original circuit. The other setups don’t match this behavior: a current source in series with a capacitor or a voltage source in parallel with an inductor alters how the circuit responds to different loads and doesn’t represent the standard Norton form. A voltage source in series with a resistor is the Thevenin equivalent, not Norton.