Inductive Reactance
Recall from the section on Inductors in DC Circuits that inductors are
the opposite of capacitors in virtually every way. As the frequency of
the alternating current increases, the opposition to current flow
presented by a capacitor (capacitive reactance) decreases. With an
inductor, it is just the opposite; as the frequency increases the
opposition to current flow (inductive reactance) increases. At
highenough frequencies an inductor is a virtual open circuit. As
opposed to capacitors, if you increase the value of an inductor,
inductive reactance increases.
Calculating Inductive Reactance
Like capacitive reactance, you need to be able to calculate the
inductive reactance for a particular inductor at a given frequency
based on the value of the inductor.
The formula to calculate inductive reactance is:
X_{L} = 2πƒL
Where:

X_{L} 
=

inductive reactance in ohms 

2π 
=

6.28 

ƒ

=

frequency in hertz 

L 
=

capacitance in henrys 
The steps to solve this formula are:
 Multiply the frequency by 6.28
 Multiply the resulting product by the inductance.
Voltage division with inductors is the same as with resistors. The greater inductance has the greater voltage.
When you apply a square wave to an inductor you get a curve that
appears identical to the one you get with a capacitor. However, the
voltage and current are reversed. You get a high peak of voltage on the
leading edge of the square. The current starts at zero then climbs to
its maximum. Meanwhile, the voltage drops to zero.
ELI
When AC is placed across an inductor there is a phase delay between
voltage and current just as in capacitors. However, in an inductor the
voltage leads the current. The acronym to remember this is ELI where E
represents voltage, L represents an inductor and I represents current.
To help remember the two acronyms think of ELI the ICE man. ELI reminds
you that voltage leads current in an inductor and ICE reminds you that
current leads voltage in a capacitor.