The maximum power transfer theorem applies to which type of networks?

The maximum power transfer theorem applies to which type of networks?

• A. Only DC circuits
• B. Only AC networks with reactance
• C. Any circuit with impedance
• D. Only circuits with purely resistive loads

Answer: (B)

In AC networks, the maximum power delivered to a load occurs when the load impedance is the complex conjugate of the source impedance. In practical terms, this means the resistive parts match and the reactive parts are opposite so they cancel out (X_L = -X_S and R_L = R_S). When the reactive components cancel, the circuit behaves as purely resistive, and the real power transfer is maximized because voltage and current are in phase. This requirement of conjugate matching relies on the presence of reactance, which is why the standard statement is framed for networks with impedance that includes reactive elements. If there were no reactance, the idea still reduces to matching resistances, but the general, widely used form centers on AC networks with reactance.

In AC networks, the maximum power delivered to a load occurs when the load impedance is the complex conjugate of the source impedance. In practical terms, this means the resistive parts match and the reactive parts are opposite so they cancel out (X_L = -X_S and R_L = R_S). When the reactive components cancel, the circuit behaves as purely resistive, and the real power transfer is maximized because voltage and current are in phase.

This requirement of conjugate matching relies on the presence of reactance, which is why the standard statement is framed for networks with impedance that includes reactive elements. If there were no reactance, the idea still reduces to matching resistances, but the general, widely used form centers on AC networks with reactance.