What is the power factor when the phase angle is 90 degrees?

The power factor is defined as the cosine of the phase angle between the voltage and current in an AC (alternating current) circuit. When the phase angle is 90 degrees, the cosine of 90 degrees is equal to 0. This indicates that there is no real power being consumed in the circuit; the power is reactive, and fixtures or devices connected in such a manner are simply drawing reactive power without performing any useful work.

In practical terms, when the power factor is 0, it means that the current is entirely out of phase with the voltage. A power factor of 1 would imply that all the power in the circuit is being used effectively, resulting in no wasted energy. A power factor of 0.5 or 0.25 would suggest that only a portion of the power is being effectively utilized. Thus, at a phase angle of 90 degrees, the power factor being 0 is the correct interpretation, demonstrating the purely reactive nature of the circuit.