What is capacitive reactance?

Capacitive reactance (Xc) is the opposition a capacitor offers to alternating current (AC). It depends on frequency (f) and capacitance (C) and is calculated as Xc = 1/(2πfC). It is measured in ohms.

How does frequency affect capacitive reactance?

Capacitive reactance is inversely proportional to frequency. As frequency increases, reactance decreases, allowing more AC current to pass. At higher frequencies, capacitors act more like short circuits.

What units should I use for frequency and capacitance?

Use hertz (Hz) for frequency and farads (F) for capacitance. The calculator will compute reactance in ohms (Ω). Ensure values are in standard units; convert if needed (e.g., microfarads to farads).

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计算器: Capacitive Reactance.

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02 / 答案

Frequency

Capacitance

reactanceOhm

2,652.58238Ω

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Cite as: Mathify. (n.d.). 计算器: Capacitive Reactance. https://mathify.one/zh/physics/capacitive-reactance

Use Cases

AC Circuit Design

Determine the reactance of a capacitor at a specific frequency to design filters, coupling circuits, or impedance matching networks.

Example: Calculate Xc for a 10 µF capacitor at 60 Hz: Xc ≈ 265 Ω.

Troubleshooting Signal Behavior

Understand how a capacitor affects signal frequencies in audio or RF circuits, helping to predict attenuation or phase shift.

Example: Check if a 0.1 µF capacitor blocks low frequencies in a speaker crossover.

Frequently Asked Questions

What is capacitive reactance?: Capacitive reactance (Xc) is the opposition a capacitor offers to alternating current (AC). It depends on frequency (f) and capacitance (C) and is calculated as Xc = 1/(2πfC). It is measured in ohms.
How does frequency affect capacitive reactance?: Capacitive reactance is inversely proportional to frequency. As frequency increases, reactance decreases, allowing more AC current to pass. At higher frequencies, capacitors act more like short circuits.
What units should I use for frequency and capacitance?: Use hertz (Hz) for frequency and farads (F) for capacitance. The calculator will compute reactance in ohms (Ω). Ensure values are in standard units; convert if needed (e.g., microfarads to farads).

Tips & Common Mistakes

Tips

Ensure frequency is in hertz (Hz) and capacitance in farads (F). Convert from kHz or µF before entering.
Remember that reactance is frequency-dependent; a capacitor's opposition changes with frequency.
Use the result to compare with resistance in series or parallel for total impedance calculations.
For DC (0 Hz), capacitive reactance is infinite, so this calculator is only for AC.

Common Mistakes to Avoid

Forgetting to convert capacitance from microfarads (µF) to farads (F) – always divide by 1,000,000.
Using frequency in kHz instead of Hz – multiply by 1000 to get Hz.
Confusing capacitive reactance with resistance – reactance is frequency-dependent and causes phase shift.

Last updated: August 13, 2026