Which statement best describes the output impedance of a circuit?

Which statement best describes the output impedance of a circuit?

• A. Impedance seen into the input of the circuit
• B. Impedance seen from the output port into the circuit
• C. Impedance seen by the load connected to the output port
• D. Impedance of the power supply

Answer: (B)

Output impedance is the impedance the circuit presents at its output terminals, i.e., what you see when you look into the circuit from the output port. This is the Thevenin resistance the load would experience connected to the output, and it governs how the output voltage changes as the load current varies. The phrasing “impedance seen from the output port into the circuit” captures exactly that viewpoint—the impedance the circuit presents to anything connected at the output. The other options describe the input side, or the power supply’s own impedance, which are not what defines the output impedance.

Output impedance is the impedance the circuit presents at its output terminals, i.e., what you see when you look into the circuit from the output port. This is the Thevenin resistance the load would experience connected to the output, and it governs how the output voltage changes as the load current varies. The phrasing “impedance seen from the output port into the circuit” captures exactly that viewpoint—the impedance the circuit presents to anything connected at the output. The other options describe the input side, or the power supply’s own impedance, which are not what defines the output impedance.