An inductor


An inductor or a reactor is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries. Typically an inductor is a conducting wire shaped as a coil, the loops helping to create a strong magnetic field inside the coil due to Faraday's law of induction. Inductors are one of the basic electronic components used in electronics where current and voltage change with time, due to the ability of inductors to delay and reshape alternating currents.

The foundation of modern electrical engineering was the discovery by Faraday that when the magnetic flux through a loop of wire was varied, a voltage was set up in the wire. This process is called electromagnetic induction.

  • A conductor wound in the form of a coil is called an inductor (or solenoid)
  • An inductor has a strong magnetic field that has many uses
  • Inductance opposes current change
  • An inductor may have its inductance increased by:-
    • adding more turns
    • introducing an iron core through the centre of the turns


Magnetic of Inductance[]

Magnetic of Turns[]

Φ = N B

Voltage of Coil's Inductance[]

= -ξ

Voltage of Coil's Turns[]

Inductive Reactance[]

Inductive reactance is equal to 2 pi times Frequency times Inductance
Xl = 2 pi FL

Phase Angle[]

For an inductor without resistance, the voltage and current is out of phase by 90o (π/2 radians).

For an inductor with resistance, the voltage and current is out of phase by θ:

Tan θ = = 2πf L/RL

When there is a change of angle, the frequency also changes. This can be used to shift the frequency:

f = ( 2π / Tanθ ) ( RL / L )

As frequency is one over time:

t = ( Tanθ / 2π ) (L / RL )

Frequency Response[]

, Shorted Circuit. I = 0
, Opened Circuit. I ‡ 0
, Shorted Circuit. I = V / 2 RL

I - can be drawn, at certain frequency the value of current does not change with. So this circuit can be used as a high pass filter.





MAKE presents The Inductor

MAKE presents: The Inductor