Inductive reactance is the opposition of an inductor to AC current, proportional to frequency. XL = 0 for DC, increases with frequency.
⚠XL unit is Ohms (Ω). Real inductors have DC resistance (DCR); total impedance Z=√(R²+XL²). Please select appropriate units.
What is Inductive Reactance?
Inductive Reactance (XL) is the opposition an inductor provides to alternating current (AC), measured in Ohms (Ω). XL is proportional to inductance (L) and frequency (f). Unlike resistance, reactance does not dissipate power; it stores energy in a magnetic field.
XL=2πfL
XL increases linearly with frequency and inductance. Doubling frequency doubles XL; doubling inductance doubles XL. XL=0 at DC.
Phase Relationship
In a pure inductor, voltage leads current by 90° (π/2 radians). Voltage peaks before current in an AC circuit.
Frequency Response
XL increases with frequency. Passes low frequencies, blocks high frequencies (low-pass filter behavior).
LC Resonance
Resonance occurs when XL=XC in LC circuits. Resonant frequency f₀=1/(2π√(LC)), fundamental for radio and RF circuits.
💡 Example: L=10mH, f=1kHz. ω=2π×1000=6283.2 rad/s. XL=2π×1000×0.01=62.83Ω. At 10kHz, XL=628.3Ω. At 50Hz, XL=3.14Ω.
What is the relationship between XL and frequency?▼
Inductive reactance XL = 2πfL is directly proportional to frequency f. Higher frequency means higher XL. At DC (f=0), XL=0 (inductor acts as short circuit). At high frequencies, XL is large, blocking high-frequency signals (choke coil).
What is the difference between reactance and resistance?▼
Resistance dissipates power as heat and is frequency-independent. Reactance stores/releases energy (magnetic field) and is frequency-dependent. Inductive reactance is imaginary impedance; voltage leads current by 90° in pure inductors.
What are the functions of inductors?▼
Inductors are used for: power supply filtering, LC oscillators, RF chokes, transformers, EMI filters, DC-DC converters, resonant circuits, and audio equipment.
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