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Power Electronic Handbook P22

Although magnetism has been known since ancient times, the connection between electricity and magnetism was not discovered until the early 19th century. Electromagnetics is the study of electric and magnetic field behavior. These fields arise from charged particles both at rest and in motion, and they may exert forces on other charged particles and materials. Hans Christian Oersted (a Danish scientist) demonstrated the relation between electricity and magnetism. In 1819, he showed that a compass needle could be deflected by a current-carrying conductor. Andrew Ampere (1775–1836) experimented with two current-carrying conductors and found that they repel or attract each. | 22 Principles of Magnetics Roman Stemprok 22.1 Introduction University of North Texas 22.2 Nature of a Magnetic Field 22.3 Electromagnetism 22.4 Magnetic Flux Density 22.5 Magnetic Circuits 22.6 Magnetic Field Intensity 22.7 Maxwell s Equations 22.8 Inductance 22.9 Practical Considerations 22.1 Introduction Although magnetism has been known since ancient times the connection between electricity and magnetism was not discovered until the early 19th century. Electromagnetics is the study of electric and magnetic field behavior. These fields arise from charged particles both at rest and in motion and they may exert forces on other charged particles and materials. Hans Christian Oersted a Danish scientist demonstrated the relation between electricity and magnetism. In 1819 he showed that a compass needle could be deflected by a current-carrying conductor. Andrew Ampere 1775-1836 experimented with two current-carrying conductors and found that they repel or attract each other. He developed a concept to understand the electromagnetism that led to the development of transformers and electric generators. The theory of electromagnetic fields was developed by James Clerk Maxwell Scottish scientist and published in 1865. His work was the culmination of a long series of experimental and theoretical research performed by a number of other scientists over the centuries. Maxwell published a set of equations that completely describe the electromagnetic field. He developed a unified theory of electromagnetism and he also predicted the existence of radio waves. Heinrich Hertz a German physicist proved the existence of such waves early in the 20th century. The electromagnetic force emf is one of the four known fundamental forces of nature. The emf is responsible for the functioning of a large number of devices that are important to modern civilization including radio television cellular telephones computers and electric machinery. The emf is caused by an electromagnetic field that is