Power factor pf is cos φ; φ is the phase angle between voltage and current; leading or lagging depending on

Power factor pf is cos φ; φ is the phase angle between voltage and current; leading or lagging depending on

• A. pf = cos φ; φ is the phase angle between voltage and current; leading for capacitive circuits and lagging for inductive.
• B. pf = cos φ; φ is the phase angle between voltage and current; always leading
• C. pf = φ; φ is the phase angle between voltage and current
• D. pf = sin φ; φ is the phase angle between voltage and current

Answer: (A)

Power factor is defined as pf = cos φ, where φ is the phase angle between the voltage and current in an AC circuit. The cosine of that angle tells you how much of the apparent power is real power. The sign or sense of φ indicates whether the current leads or lags: in a capacitive circuit the current leads the voltage, while in an inductive circuit the current lags the voltage. Because pf is cos φ, the magnitude is between 0 and 1 and the leading/lagging behavior comes from whether the circuit is capacitive or inductive. This matches the statement that pf equals cos φ, φ is the phase angle between voltage and current, and the system is leading for capacitive and lagging for inductive. The other options misstate the relationship (pf is not φ or sin φ, and it is not always leading).

Power factor is defined as pf = cos φ, where φ is the phase angle between the voltage and current in an AC circuit. The cosine of that angle tells you how much of the apparent power is real power. The sign or sense of φ indicates whether the current leads or lags: in a capacitive circuit the current leads the voltage, while in an inductive circuit the current lags the voltage. Because pf is cos φ, the magnitude is between 0 and 1 and the leading/lagging behavior comes from whether the circuit is capacitive or inductive. This matches the statement that pf equals cos φ, φ is the phase angle between voltage and current, and the system is leading for capacitive and lagging for inductive. The other options misstate the relationship (pf is not φ or sin φ, and it is not always leading).