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.

Learning Objectives

Upon completion of this course, participants will be able to:

• Describe inductors and their applications in DC circuits.
• Explain the derivation of the henry as a unit of inductance in the International System of Units.
• Identify common smaller units of inductance used in practice.
• Describe the method used to measure reactance.
• Distinguish electromotive force (EMF) from voltage.
• Explain the materials and processes used to manufacture inductor cores.
• Describe the composition and shaping process of ferrite inductor cores.
• Explain the purpose and construction of laminated cores.
• Define toroids and describe their use in inductor design.
• Describe the design and construction of variable inductors.
• Distinguish ferrous metals from nonferrous metals.
• Identify examples of inductors wound on different core types.
• Interpret American and international schematic symbols for inductors.
• Explain how water analogies can be used to interpret electrical schematics.
• Analyze voltage and current plot characteristics during an inductor’s transient response.
• Compare inductors with their dual components, capacitors.
• Describe the primary properties of magnetic flux lines.
• Apply basic equations used to analyze inductance.
• Explain Lenz’s law of magnetism and its practical applications.
• Apply the right-hand rule to determine the direction of magnetic flux.
• Interpret inductor charge and discharge plots and their corresponding water analogies.
• Explain the process of energy storage in an inductor’s magnetic field.
• Distinguish ideal inductors from real-world inductors.
• Analyze the effects of core losses, hysteresis, and retentivity on inductor performance.
• Interpret a hysteresis loop and explain its effect on inductor behavior.
• Describe the use of chokes in electronic circuits.
• Calculate total inductance in series and parallel configurations.
• Explain the function and applications of electromagnets.
• Describe the construction and uses of solenoids.
• Explain the role of magnetism in basic DC motor and generator design.
• Construct and test a simple electromagnet.
• Measure and calculate core permeability in electromagnets.
• Compare the lifting strength of simple and horseshoe electromagnets.
• Specify inductors for purchase 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.