AT&T Technical Knowledge (TKT) II Practice Test

The power factor in an AC circuit is primarily a measure of efficiency, indicating how effectively the electrical power is being converted into usable work output. It is defined as the cosine of the phase angle between the voltage and current waveforms and represents the ratio of real power (the power that actually does work) to apparent power (the total power flowing in the circuit). A power factor of 1 (or 100%) implies that all the power is being effectively converted to work, while lower values indicate that not all the power is being used efficiently, often due to the presence of reactive components in the circuit.

This relationship illustrates the losses in an electrical system and how much of the apparent power contributes to productive work versus how much is reactive power, which does not perform useful work but is necessary for maintaining the electric and magnetic fields in inductive and capacitive loads. In practical applications, a higher power factor represents better efficiency in power delivery.

Other options, while related to the behavior of AC circuits, do not directly address what power factor measures. Voltage relates to the electrical potential difference, reactance deals with the opposition to alternating current due to capacitors and inductors, and resistance refers to the opposition to current flow in a conductor. None of these focus