This all-in-one online Inductive Reactance Calculator performs calculations using the formula that relates the frequency of alternating current and the inductance of an electrical circuit to its reactance. You can enter the values of any two known parameters in the input fields of this calculator and find the missing parameter.
Inductive Reactance Formula
Inductive reactance is a property of an induction coil that resists changes in the alternating current (AC) flowing through it and in this sense is analogous to the resistance to direct current (DC) in resistors.
When an inductor coil is connected to a voltage source, an electric current begins to flow through the coil and creates a magnetic field around it. If the strength of the current increases over time, this increases the strength of the magnetic field.
This amplification of the magnetic field induces in turn an electric current in the coil itself (counter EMF). The induced current is directed in the opposite direction to the flowing current generated by the external voltage source.
Similarly, when the current from an external source decreases, the induced current is generated as a result of self-induction, preventing the current flowing through the coil from decreasing.
Therefore, inductive reactance manifests itself as an opposition to the change of current through the inductive element.
It is intuitively clear that the greater the inductance of the coil (and therefore the magnetic field it generates and the induced current) and the higher the frequency of alternating current, the greater the inductive reactance.
Although the inductive reactance is different from the resistance of a resistor, but it is measured in Ohms just the same. Inductive reactance is used instead of ordinary resistance in calculations using Ohm’s law.
The inductive reactance of a circuit is expressed by the following formula, which is used in our Inductive Reactance Calculator:
$$X_L = 2\pi fL,$$
where
\(X_L\) is the inductive reactance measured in the SI system in ohm (Ω). Dimension: M·L2·T-3·I-2,
\(L\) is the inductance measured in the SI system in henry (H). Dimension: M·L2·T-2·I-2,
\(f\) is the frequency measured in the SI system in hertz (Hz) : 1 Hz = 1 sec -1 .
It is important to emphasize that inductive reactance differs from conventional resistance. The current and voltage for an inductor are 90° out of phase, whereas for a resistor they are in phase. As a result, the resistance of the resistor \(R\) and the inductive reactance \(X_L\) cannot be added up directly. Instead, they should be summed up ‘vectorially’:
$$X_{total} = \sqrt{X_L^2+R^2}.$$
In addition, inductive reactance does not dissipate electrical energy in the form of heat. Instead, energy is stored in the inductor for a while and returned to the circuit after a quarter of a cycle, while the usual resistance constantly loses energy.
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Check out our other physics calculators such as Ohm’s Law Calculator or Resonant Frequency Calculator.