Which of the following about capacitive reactance is correct?

The correct answer is Option (2) → Capacitive reactance is inversely proportional to the frequency of the current.

The capacitive reactance is \( X_C=1/\omega C \). It limits the current in a capacitive circuit as a resistance does in a resistive one.

Option (1) The reactance of a capacitor is directly proportional to its ability to store charge. — Incorrect. The ability to store charge is the capacitance C. Since \( X_C=1/\omega C \) falls as C rises, the reactance is inversely proportional to the capacitance.

Option (2) Capacitive reactance is inversely proportional to the frequency of the current. — Correct. Since \( X_C=1/(2\pi\nu C) \), doubling the frequency halves the reactance. At high frequency the plates charge and discharge quickly, so a larger current flows for the same voltage.

Option (3) Capacitive reactance is measured in henry. — Incorrect. Reactance has the same dimension as resistance, and its SI unit is the ohm. The henry is the unit of inductance.

Option (4) The reactance of a capacitor in an ac circuit is similar to a battery in a dc circuit. — Incorrect. A battery is a source of emf, while the reactance opposes the current. It plays the same part as a resistance in a dc circuit.

NCERT (2026-27):
AC Voltage Applied to a Capacitor – “The dimension of capacitive reactance is the same as that of resistance and its SI unit is ohm (Ω). The capacitive reactance limits the amplitude of the current in a purely capacitive circuit in the same way as the resistance limits the current in a purely resistive circuit. But it is inversely proportional to the frequency and the capacitance.”