Inductors: The
Fundamentals
Inductors are passive electrical components that store energy in a
magnetic field. They are essential for a wide range of electronic circuits
and systems. This presentation will explore the fundamental aspects of
inductors, from their basic definition to their diverse applications.
by Ayushi
Inductance and its
Measurement
Inductance is a measure of an inductor's ability to store energy in a
magnetic field. It is measured in Henrys (H). The inductance of an
inductor depends on its physical characteristics, such as the number of
turns of wire, the core material, and the geometry of the coil.
1 Inductance Formula 2 Measurement
The inductance of a coil is
Techniques
directly proportional to the Inductance can be
square of the number of measured using various
turns, the permeability of methods, including LCR
the core, and the cross- meters and bridge circuits.
sectional area of the coil.
3 Inductance Units
The standard unit of inductance is the Henry (H), named after
the American scientist Joseph Henry.
Types of Inductors
Inductors come in various forms, each designed for specific applications. The most common types include air core inductors,
iron core inductors, and ferrite core inductors. Each type has unique characteristics that influence its performance and
suitability for different circuits.
Air Core Iron Core Ferrite Core
Air core inductors are characterized Iron core inductors utilize a Ferrite core inductors employ a
by their simple construction, typically ferromagnetic core, typically made of ceramic-like material known as
consisting of a coil of wire wound iron or steel, to increase inductance. ferrite. This material offers high
around a non-magnetic core. These These inductors offer higher permeability and low losses, making
inductors are known for their high Q inductance values and lower losses ferrite core inductors suitable for a
factor and stability, making them compared to air core inductors, wide range of applications,
suitable for high-frequency making them ideal for low-frequency particularly in the radio frequency
applications. applications. (RF) range.
Factors Affecting Inductance
Several factors determine the inductance of an inductor, each playing a
critical role in its performance. Understanding these factors allows
engineers to design inductors that meet specific requirements for their
applications.
1 Number of Turns
Increasing the number of turns in a coil directly
increases its inductance. This is because more turns
create a stronger magnetic field.
2 Core Material
The permeability of the core material significantly
affects inductance. Materials with higher permeability,
such as iron and ferrite, increase inductance.
3 Coil Geometry
The geometry of the coil, including its length, cross-
sectional area, and shape, influences inductance. Longer
coils and larger cross-sectional areas generally result in
higher inductance.
Applications of Inductors
Inductors have widespread applications in electronic circuits and
systems, playing crucial roles in filtering, energy storage, and signal
processing. Their ability to store energy in magnetic fields makes them
indispensable for various functionalities.
Filters Energy Storage
Inductors are used in filter Inductors store energy in a
circuits to block or pass magnetic field, making them
specific frequencies. They are useful in applications like
particularly important in switching power supplies and
power supplies and audio energy harvesting.
systems.
Signal Processing
Inductors are used in signal processing circuits to shape and
manipulate signals, particularly in communication systems.
Inductor Behavior in AC Circuits
In AC circuits, inductors exhibit unique behavior due to the alternating current flow. They oppose changes in current, resulting
in a phase shift between the voltage and current waveforms.
1 2 3
Inductive Reactance Phase Shift Energy Storage and Release
Inductive reactance (XL) is the The voltage across an inductor leads Inductors store energy in their
opposition to current flow caused by the current through it by 90 degrees magnetic field during the rising
an inductor in an AC circuit. It is in an AC circuit. This phase shift is a portion of the AC cycle and release
directly proportional to the frequency consequence of the inductor's energy during the falling portion.
of the AC signal. opposition to current changes.
Inductor Behavior in DC
Circuits
In DC circuits, inductors behave differently than in AC circuits. They
oppose changes in current, but once the current stabilizes, they act as
short circuits, allowing DC to flow through them without resistance.
DC Circuit Inductor Behavior
Current On Inductor resists changes in
current, causing a voltage drop
across it. The inductor acts as a
temporary open circuit.
Current Steady Inductor behaves as a short
circuit, allowing DC current to
flow without resistance.
Current Off Inductor opposes the decrease
in current, creating a voltage
spike across it. This voltage
spike can be significant,
especially for large inductances.
Inductor Design Considerations
Designing inductors requires careful consideration of several factors to achieve the desired performance and suitability for the
intended application. These considerations ensure that the inductor meets specific requirements for inductance, current rating,
and frequency range.
Efficiency Temperature Rating Physical Size Cost
Minimizing losses due to The operating temperature The physical size and shape The cost of the inductor is
resistance, core losses, and range of the inductor must of the inductor should be an important consideration,
stray inductance is crucial be considered, as excessive appropriate for the balancing performance and
for efficient inductor heat can degrade application and its budget requirements.
operation. performance. surrounding environment.
