What occurs to the power factor (PF) when the phase angle increases?

The relationship between phase angle and power factor is fundamental in understanding the behavior of AC circuits. The power factor is defined as the cosine of the phase angle (PF = cos(ϕ)), where ϕ represents the phase angle between the voltage and current. As the phase angle increases, the cosine of that angle decreases.

When the phase angle approaches 90 degrees, the cosine value approaches zero, meaning the power factor likewise approaches zero, indicating that the circuit is becoming less efficient in converting electrical power into useful work. Therefore, an increase in the phase angle leads to a decrease in the power factor, reflecting a greater proportion of reactive power relative to active power in the system.

In practice, this means that as the phase angle increases, the circuit becomes predominantly reactive, and the overall efficiency and effectiveness in delivering power decreases. Hence, the correct choice highlights that the power factor indeed decreases as the phase angle increases.