What is the name for the ratio of real power dissipated to the apparent input power?

What is the name for the ratio of real power dissipated to the apparent input power?

• A. Efficiency
• B. Impedance
• C. Power Loss
• D. Power Factor

Answer: (D)

In AC circuits, real (active) power is the portion that actually does useful work, while apparent power is the total power that flows, calculated from voltage and current regardless of how it’s used. The ratio of real power dissipated to the apparent input power is called the power factor. It’s defined as P divided by S, which also equals cos(phi), where phi is the phase angle between voltage and current. When voltage and current are in phase (purely resistive load), the power factor is 1, meaning all the input power is doing useful work. If there is reactance (inductive or capacitive), part of the power is stored temporarily and returned, so the power factor drops below 1. The other terms—efficiency, impedance, and power loss—describe different concepts and do not represent this ratio.

In AC circuits, real (active) power is the portion that actually does useful work, while apparent power is the total power that flows, calculated from voltage and current regardless of how it’s used. The ratio of real power dissipated to the apparent input power is called the power factor. It’s defined as P divided by S, which also equals cos(phi), where phi is the phase angle between voltage and current. When voltage and current are in phase (purely resistive load), the power factor is 1, meaning all the input power is doing useful work. If there is reactance (inductive or capacitive), part of the power is stored temporarily and returned, so the power factor drops below 1. The other terms—efficiency, impedance, and power loss—describe different concepts and do not represent this ratio.