Which device provides capacitive reactance in a circuit?

• A. Resistor
• B. Inductor
• C. Capacitor
• D. Transformer

Answer: (C)

Capacitive reactance comes from the capacitor’s ability to store and release charge in an AC circuit, which opposes the current flow. This opposition is described by Xc = 1/(2πfC): it decreases as frequency or capacitance increases. In DC, a capacitor blocks current once charged, acting like an open circuit, while in AC it presents this reactive opposition. Resistors don’t create reactance; they offer pure resistance with no phase shift. Inductors create inductive reactance, causing current to lag voltage. A transformer isn’t a source of capacitive reactance by itself, since it relies on inductive effects.