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Capacitor & Reactance Calculator

Calculate capacitive reactance (Xc), stored energy (Joules), and series/parallel capacitor network values.

1. Enter your numbers  →  2. Check the answer  →  3. Read the steps before you trust it

Hz
V

Capacitive Reactance & Energy

Capacitive Reactance (Xc)
265.258 Ω

Opposition to AC current at 60 Hz

Stored Electrostatic Energy (E)
0.072 Joules (72.000 mJ)

@ 120 V applied

Step-by-Step Engineering Calculation

  1. 1Angular Frequency: ω=2π×60 Hz=376.99 rad/s\omega = 2\pi \times 60\text{ Hz} = 376.99\text{ rad/s}
  2. 2Reactance Formula: XC=\ rac12π imesf imesCX_C = \ rac{1}{2\pi \ imes f \ imes C}
  3. 3Capacitive Reactance: XC=12π×60×1.0000e−5=265.2582 ΩX_C = \frac{1}{2\pi \times 60 \times 1.0000e-5} = \mathbf{265.2582\ \Omega}
  4. 4Stored Energy: E=12×C×V2=12×1.0000e−5 F×(120 V)2=0.072000 JE = \frac{1}{2} \times C \times V^2 = \frac{1}{2} \times 1.0000e-5\text{ F} \times (120\text{ V})^2 = \mathbf{0.072000\text{ J}} (72.000 mJ)

Formula & Theory

X_C = 1 / (2π × f × C) | E = ½ × C × V²

Computes AC opposition to current (reactance in Ohms) and electrostatic stored potential energy in Joules.

Variable Definitions
X_C:
Reactance (Ohms (Ω)) – Opposition to AC current flow
f:
Frequency (Hertz (Hz)) – AC signal frequency
C:
Capacitance (Farads (F / µF / nF / pF)) – Electrical capacitance
E:
Stored Energy (Joules (J)) – Electrostatic energy stored in electric field

Worked Engineering Example

10µF Filter Capacitor at 60Hz

A 10µF capacitor operating in a 120V 60Hz AC filter circuit.

Inputs:
  • Frequency: 60 Hz
  • Capacitance: 10 µF
  • Voltage: 120 V
Result: Reactance Xc = 265.26 Ω | Stored Energy = 0.072 J (72 mJ)

Key Assumptions

  • •Sinusoidal AC waveform.

Limitations & Safety Scope

  • •Does not include dielectric loss (Equivalent Series Resistance, ESR).

Frequently Asked Questions

Why does capacitive reactance decrease as frequency increases?

As frequency rises, the capacitor charges and discharges more frequently per second, allowing more charge to move per unit time, which reduces the effective opposition (reactance) to AC current.

Related Calculators & Engineering Tools

Power Factor Calculator
Ohm's Law Calculator

Educational & Reference Notice: This calculator provides technical estimates based on standard physical formulas. Actual electrical installation, protective device sizing, and conductor selection must be verified against the applicable electrical code (NEC, IEC, CEC) by a licensed electrician or qualified professional engineer.