Inductive Reactance Calculator
Free calculate inductive reactance (xl) from frequency and inductance using xl = 2πfl. Get instant, accurate results with our easy-to-use calculator.
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What is Inductive Reactance?
Inductive reactance (XL) is the opposition an inductor presents to alternating current (AC) due to its inductance. Unlike resistance, reactance depends on frequency.
Inductors oppose changes in current by generating a back-EMF. In AC circuits, this opposition increases with frequency - higher frequencies mean more opposition. At DC (0 Hz), inductors have zero reactance (act like short circuits).
Inductive reactance is measured in ohms (Ω) and is crucial in AC circuit analysis, filter design, transformers, and understanding how inductors behave in different frequency ranges.
Inductive Reactance Formula
Where:
- • X_L = Inductive reactance (Ω)
- • f = Frequency (Hz)
- • L = Inductance (H)
- • π = 3.14159...
Note: Reactance increases linearly with both frequency and inductance.
How to Calculate Inductive Reactance
-
1
Convert frequency to Hz
Convert kHz or MHz to Hz (1 kHz = 1000 Hz, 1 MHz = 1,000,000 Hz).
-
2
Convert inductance to Henries
Convert mH or μH to H (1 mH = 0.001 H, 1 μH = 0.000001 H).
-
3
Apply the formula
Calculate X_L = 2πfL using π ≈ 3.14159.
Practical Examples
Example 1: 60 Hz Power Line
An inductor with 0.1 H inductance is used in a 60 Hz AC circuit. Calculate reactance.
Solution:
X_L = 2πfL = 2 × π × 60 Hz × 0.1 H
X_L = 37.7 Ω
Example 2: Radio Frequency
A 10 μH inductor at 1 MHz. What is the reactance?
Solution:
L = 10 μH = 0.00001 H, f = 1 MHz = 1,000,000 Hz
X_L = 2π × 1,000,000 × 0.00001
X_L = 62.8 Ω
Applications
AC Circuits
Understanding impedance, phase relationships, and current behavior in AC power systems and electronics.
Filters
Designing low-pass, high-pass, and band-pass filters using inductive reactance to block or pass frequencies.
Transformers
Understanding how transformers work and calculating impedance matching in power and signal transformers.
RF Circuits
Radio frequency circuits, antennas, and communication systems where frequency-dependent impedance matters.
Frequently Asked Questions
Why does reactance increase with frequency?
Higher frequency means current changes faster. Inductors oppose current changes, so faster changes mean more opposition (higher reactance).
What is the difference between reactance and resistance?
Resistance (R) opposes all current and dissipates energy as heat. Reactance (X) opposes AC current changes, stores energy in magnetic fields, and doesn't dissipate power.
What happens at DC (0 Hz)?
At DC, X_L = 0 (since f = 0). Inductors act like short circuits at DC, allowing current to flow with only wire resistance.
How does reactance affect phase?
In inductors, voltage leads current by 90°. The reactance causes this phase shift, which is important in AC circuit analysis.
What is impedance?
Impedance (Z) combines resistance and reactance: Z = √(R² + X²). For pure inductance, Z = X_L. Impedance determines current in AC circuits: I = V/Z.