Final answer:
Capacitive reactance is the opposition that a capacitor presents to AC, analogous to resistance in DC circuits and measured in ohms. It is inversely proportional to both the frequency of the AC source and the capacitance of the capacitor itself.
Step-by-step explanation:
The measure of how much a capacitor is able to oppose the flow of Alternating Current (AC) is called capacitive reactance. This is analogous to resistance in a Direct Current (DC) circuit in that both are a ratio of voltage to current and are measured in ohms. However, unlike a resistor, which dissipates energy, a capacitor stores and discharges electrical energy. Capacitive reactance (Xc) depends inversely on the frequency of the AC source; a higher frequency translates to a lower Xc.
The formula for calculating capacitive reactance is Xc = 1/(2πfC), where 'f' is the frequency and 'C' is the capacitance. The greater the capacitance of the capacitor, the more charge it can store, and, consequently, the larger the current that can flow before the capacitor limits it. When fully charged, a capacitor can stop current, thus acting as an effective resistance to AC. This effect is amplified at lower frequencies because the capacitor has more time to charge fully, resulting in greater opposition to current flow.