How to Calculate Capacitive Reactance

Capacitive Reactance Formula:

\[ X_c = \frac{1}{2 \pi f C} \]

Capacitive Reactance (X_c):

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1. What is Capacitive Reactance?

Capacitive reactance (X_c) is the opposition that a capacitor offers to alternating current (AC) due to its capacitance. Unlike resistance, reactance varies with frequency.

2. How Does the Calculator Work?

The calculator uses the capacitive reactance formula:

\[ X_c = \frac{1}{2 \pi f C} \]

Where:

\( X_c \) — Capacitive reactance in ohms (Ω)
\( f \) — Frequency in hertz (Hz)
\( C \) — Capacitance in farads (F)
\( \pi \) — Mathematical constant (~3.14159)

Explanation: The reactance decreases with increasing frequency or capacitance. At DC (0 Hz), the reactance is theoretically infinite (open circuit).

3. Importance of Capacitive Reactance

Details: Understanding capacitive reactance is essential for designing AC circuits, filters, timing circuits, and impedance matching networks.

4. Using the Calculator

Tips: Enter frequency in Hz and capacitance in farads (F). For microfarads (μF), multiply by 10^-6. For nanofarads (nF), multiply by 10^-9.

5. Frequently Asked Questions (FAQ)

Q1: Why does reactance decrease with frequency?
A: At higher frequencies, the capacitor has less time to charge/discharge, effectively offering less opposition to current flow.

Q2: What happens at DC (0 Hz)?
A: The reactance becomes infinite, which is why capacitors block DC current.

Q3: How is reactance different from resistance?
A: Reactance is frequency-dependent and doesn't dissipate energy like resistance does. It stores energy in the electric field.

Q4: What is the phase relationship in capacitive circuits?
A: Current leads voltage by 90° in a purely capacitive circuit.

Q5: How does reactance affect power in AC circuits?
A: Capacitors don't consume real power but create reactive power, affecting the power factor.