Reactive power is present when the current and voltage are in phase.

Reactive power is present when the current and voltage are in phase.

• A. True
• B. Not defined
• C. Depends on frequency
• D. False

Answer: (D)

Reactive power comes from energy stored and returned by inductors and capacitors, which shows up when voltage and current are not in sync. If the voltage and current are in phase, the phase angle is zero, so the reactive component is zero (Q = VI sin φ with φ = 0). That means all the power is real power delivered to resistive elements, and there’s no energy oscillating between the source and the reactive elements. Frequency affects the values of reactance, but it doesn’t create reactive power by itself; it’s the phase difference that matters. So the statement is false.

Reactive power comes from energy stored and returned by inductors and capacitors, which shows up when voltage and current are not in sync. If the voltage and current are in phase, the phase angle is zero, so the reactive component is zero (Q = VI sin φ with φ = 0). That means all the power is real power delivered to resistive elements, and there’s no energy oscillating between the source and the reactive elements. Frequency affects the values of reactance, but it doesn’t create reactive power by itself; it’s the phase difference that matters. So the statement is false.