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Magnetically Coupled Circuits

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Magnetically Coupled Circuits

If you would increase your happiness and prolong your life, forget your neighbor’s faults… . Forget the peculiarities of your friends, and only remember the good points which make you fond of them… . Obliterate everything disagreeable from yesterday; write upon today’s clean sheet those things lovely and lovable.

—Anonymous

chapter

13

Enhancing Your Career

Career in Electromagnetics

Electromagnetics (EM) is the branch of electrical engineering (or ph ysics) that deals with the analysis and application of electric and magnetic fields. In electromagnetics, electric circuit analysis is applied at low frequencies.

The principles of EM are applied in various allied disciplines, such as electric machines, electromechanical ener gy conversion, radar meteorology, remote sensing, satellite communications, bioelectromagnetics, electromagnetic interference and compatibility, plasmas, and fiber optics. EM devices include electric motors and generators, transformers, electromagnets, magnetic levitation, antennas, radars, microwave ovens, microwave dishes, superconductors, and electrocardiograms. The design of these de vices requires a thorough knowledge of the laws and principles of EM.

EM is regarded as one of the more dif ficult disciplines in electrical engineering. One reason is that EM phenomena are rather abstract. But if one enjoys working with mathematics and can visualize the invisible, one should consider being a specialist in EM, inasmuch as few electrical engineers specialize in this area. Electrical engineers who specialize in EM are needed in micro wave industries, radio/TV broadcasting stations, electromagnetic research laboratories, and se veral communications industries.

Telemetry receiving station for space satellites. © DV169/Getty Images RF

Historical

© Bettmann/Corbis

James Clerk Maxwell (1831–1879), a graduate in mathematics from Cambridge University, in 1865 wrote a most remarkable paper in which he mathematically unified the laws of Faraday and Ampere. This relationship between the electric field and magnetic field served as the basis for what was later called electromagnetic fields and waves, a major field of study in electrical engineering. The Institute of Electrical and Electron ics Engineers (IEEE) uses a graphical representation of this principle in its logo, in which a straight arrow represents current and a curved arrow represents the electromagnetic field. This relationship is commonly known as the right-hand rule . Maxwell was a very active theoretician and scientist. He is best known for the “Maxwell equations.” The max well, a unit of magnetic flux, was named after him.

Learning Objectives

By using the information and exercises in this chapter you will be able to:

    1. Understand the physics behind mutually coupled circuits and how to analyze circuits containing mutually coupled inductors.
    1. Understand how energy is stored in mutually coupled circuits.
    1. Understand how linear transformers work and how to analyze circuits containing them.
    1. Understand how ideal transformers work and how to analyze circuits containing them.
    1. Understand how ideal auto transformers work and know how to analyze them when used in a variety of circuits.