What is Reactance?

Reactance (symbolized by X) is the opposition that a circuit element presents to an alternating current (AC) due to its inductance or capacitance. Unlike pure resistance, reactance does not dissipate energy as heat; instead, it stores energy temporarily in electric or magnetic fields. It is measured in Ohms (Ω).

Inductive Reactance (XL)

Inductive reactance is the opposition provided by an inductor. The formula is XL = 2πfL. As the frequency (f) of the AC signal increases, the inductive reactance also increases. This is why inductors block high-frequency signals and pass low-frequency signals (acting as a low-pass filter component).

Capacitive Reactance (XC)

Capacitive reactance is the opposition provided by a capacitor. The formula is XC = 1 / (2πfC). Unlike inductors, capacitors show high reactance at low frequencies and low reactance at high frequencies. At DC (0 Hz), a capacitor theoretically has infinite reactance, effectively blocking the current.

How to Use This Calculator

To use this reactance calculator with steps, follow these instructions:

• Select the Reactance Type (Inductive or Capacitive) from the dropdown.
• Enter the Frequency and select the appropriate unit (Hz, kHz, or MHz).
• Enter the Component Value (Inductance in Henrys or Capacitance in Farads) and select its multiplier (milli, micro, nano, pico).
• Click Calculate Now to see the result and the step-by-step mathematical breakdown.

Frequently Asked Questions

Q: Why is reactance measured in Ohms?
A: Even though it relates to energy storage rather than dissipation, it still restricts the flow of current just like resistance, so the unit of measure remains the Ohm.

Q: What happens at resonance?
A: Electrical resonance occurs in a circuit when inductive reactance and capacitive reactance are equal in magnitude but opposite in phase, often cancelling each other out.