Before starting this module, you should be able to: When you complete this module, you should be able to: 
  • Define inductance and describe its schematic symbol.
  • Cite the units of measure for inductance.

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  • Define inductive reactance.
  • Describe the effect that inductive reactance has upon the amount of current flowing in an AC circuit.

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 Inductive Reactance
Inductive reactance is the opposition to AC current flow that is caused by the presence of an inductor in the circuit.
  • The symbol for inductive reactance is XL.
  • The units of measure for inductive reactance is ohms, W.
The amount of inductive reactance in a circuit is proportional to:
  • Applied frequency,  f
  • Value of the inductor, L

Inductive reactance is an AC version of resistance. In fact, you can use Ohm's Law by substituding XL for R:

VL = ILXL where:

    VL is the voltage across the inductor in volts
     IL is the current through the inductor in amperes
    XL is the amount of inductive reactance in ohms