Power factor of a pure capacitor is

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zero leading

Explanation: The power factor of a pure capacitor is always zero leading. This occurs because the current in a purely capacitive circuit leads the voltage by an angle of $90^\circ$ (or $\frac{\pi}{2}$ radians).

Working Principle: In a pure capacitor, the current is given by $i(t) = C \frac{dv}{dt}$. When a sinusoidal voltage $v(t) = V_m \sin(\omega t)$ is applied, the current becomes $i(t) = \omega C V_m \sin(\omega t + 90^\circ)$. Since the phase difference $\phi$ between voltage and current is $90^\circ$, the power factor $\cos(\phi) = \cos(90^\circ) = 0$, and the current leads the voltage.

Key Formulas: $i = C \frac{dv}{dt}$ — Current-Voltage relationship in a capacitor; $PF = \cos(\phi)$ — Power Factor definition where $\phi$ is the phase angle

Key Points: Pure capacitive load consumes zero active power.; The current waveform leads the voltage waveform by $90^\circ$.; Power factor improvement uses shunt capacitors to neutralize inductive lagging current.

Advantages: Used to improve overall power factor of industrial loads.; Reduces transmission line losses ($I^2R$ losses).

Disadvantages: Over-correction can lead to unwanted voltage rise.; Harmonics can cause stress on capacitive components.

Applications: Power factor correction banks.; Coupling capacitors in communication systems.

Additional Info: In a purely resistive circuit, the power factor is unity ($1.0$).. In a purely inductive circuit, the power factor is zero lagging.. Option C refers to a pure inductor, not a capacitor.

Answer: B is correct — In a purely capacitive circuit, the phase angle between voltage and current is $90^\circ$ with current leading, resulting in a zero leading power factor.

Exam Tip: Remember the mnemonic 'ELI the ICE man': for Inductor (L), E leads I; for Capacitor (C), I leads E.

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