Electronics You Might Not Have Learned in College Lesson 4: Introduction to Inductors, Coils, Electromagnets, and DC Motors

In Electronics You Might Not Have Learned in College Lesson 4: Introduction to Inductors, Coils, Electromagnets, and DC Motors, you'll learn ...

• The fundamental principles of inductance—including the behavior of inductors in DC circuits, the role of magnetic fields, and how energy is stored and released in inductors.
• Different types of inductors and cores—such as air-core, laminated, ferrite, and toroidal designs—and how core material and construction affect performance and application.
• How to apply water analogies and schematic interpretations to analyze RL circuits, transient response, step functions, and inductive charge/discharge behaviors for better conceptual understanding.
• Real-world applications of inductors—including solenoids, electromagnets, chokes, and DC motors—and how to calculate parameters such as inductance, permeability, and time constants relevant to engineering practice.

Overview

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Credit: 6 PDH

Length: 81 pages

This course offers a comprehensive introduction to inductors and related magnetic components, intended for engineers with varying backgrounds in electronics. Part of the “Electronics You Might Not Have Learned in College” series, Lesson 4 covers the foundational principles, design considerations, and real-world applications of inductors, coils, and electromagnets in direct current (DC) circuits.

The lesson begins by clarifying the basic operation of inductors, which are passive components that store energy in magnetic fields. Through the extensive use of water analogies, students are introduced to the concepts of inductance, magnetic field behavior, and energy storage. The lesson carefully builds up to more complex topics such as RL circuit time constants, transient responses, and the mathematical derivation of the henry—the SI unit of inductance.

Numerous types of inductors are explored, including air-core, laminated, ferrite, and toroidal variants. Practical aspects like core materials, coil winding, and inductive reactance are addressed in detail. The course also explains phenomena like Lenz’s Law, magnetic flux, core losses, hysteresis, and Curie point demagnetization, all supported by illustrative analogies and circuit diagrams.

In addition to theoretical content, the course provides real-world examples such as solenoids, relays, and electromagnets. It culminates with the construction and analysis of a simple electromagnet, including calculations for core permeability. The relative permeability of the simple core is calculated, but also an enhanced U-core will be made using the same coil to show the additional effectiveness of the enhanced magnetic field path. The math involved with calculating the permeability of a simple electromagnet will be demonstrated and the effect of alloys and treatment methods on the permeability of steel and iron cores will also be investigated.

The lesson ends with guidance on sourcing and specifying inductors, making it both technically enriching and immediately applicable for engineers. A sample catalog page is shown including instructions on how to use the data on it. A short section is included to help with finding a source for the right inductor. While the many online electronic sources have helpful guides to their many products, it is essential to know what specifications the inductor should meet to provide good operation over a long life.

Designed to refresh and expand understanding, this course balances foundational theory with practical insight, using relatable analogies to demystify the physics of inductance and magnetism in DC electronics.

Specific Knowledge or Skill Obtained

This course teaches the following specific knowledge and skills:

• Inductors and their applications in direct current circuits
• The derivation of the measurement unit Henries from the International System of Measurements
• Common smaller units of inductance used in practice
• The method for measuring reactance
• The distinction between electromotive force (EMF) and voltage
• The materials and processes used in manufacturing inductor cores
• The composition and shaping process of ferrite inductor cores
• The purpose and construction of laminated cores
• The definition and usage of toroids in inductor design
• The design and construction of variable inductors
• The differences between ferrous and non-ferrous metals
• Examples of inductors wound on various types of cores
• American and international schematic symbols for inductors
• The use of water analogies to explain electrical schematics
• Voltage and current plot characteristics during an inductor’s transient response
• A comparison between inductors and their dual components, capacitors
• The primary properties of magnetic flux lines
• Basic equations used in analyzing inductance
• Lenz’s Law of magnetism and its practical applications
• The right-hand rule of magnetic flux and its usage
• The drawing and interpretation of inductor charge and discharge plots, along with corresponding water analogies
• The process of energy storage in an inductor’s magnetic field
• Differences between ideal (imaginary) and real-world inductors
• The impact of core losses, hysteresis, and retentivity on inductor performance
• The concept and plotting of a hysteresis loop and its effect on inductor behavior
• The use of chokes in electronic circuits
• The method for calculating total inductance in series and parallel configurations
• The function and application of electromagnets
• The construction and uses of solenoids
• The role of magnetism in basic DC motor and generator design
• The steps for building and testing a simple electromagnet
• The techniques for measuring and calculating core permeability in electromagnets
• The difference in lifting strength between simple and horseshoe electromagnets
• The process for specifying and purchasing inductors from online vendors

Certificate of Completion

You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 35 questions. PDH credits are not awarded until the course is completed and quiz is passed.