Both electrostatic and magnetic phenomena were being written about around 2500 years ago. The magnetic compass appears to have taken a further 1.5 millennia to appear and a mere 180 years ago came the first clear observation of connection between electricity and magnetism when Hans Christian Oersted, here in Copenhagen, noticed that a current flowing in a wire affected a nearby compass.
Many small steps in technology were needed before even this simple observation could be made, means of generating electric currents were required for example, for which the battery needed to have been invented and electrical conductors made. At that time many of the necessary new technologies were being put in place and the pace of change was set for a dramatic increase. When Michael Faraday in 1831 discovered electromagnetic induction, he made possible electric power enabling virtually all of the technology upon which our present civilisation depends. His earth-shaking discovery must rank with the greatest discoveries of all time if it is not actually the very greatest.
Some 50 years later James Clerk Maxwell described mathematically in a series of 'equations' the electromagnetic field discovered by Faraday, these have stood the test of time and remain substantially unaltered a 100 years later.
Before those famous equations were available to guide the experimenter, Faraday's discovery had triggered a whole field of study, experiment and invention which grew explosively and which in 1879 had already resulted in the invention of systems using Eddy Current technology for the purpose of comparing properties of metals and alloys including measurements of conductivity and permeability, weights of coins and demonstrations of skin effect together with experiments in pulsed Eddy Current technology which until recently this author had felt to be amongst the very latest and most avant-garde techniques. It's 120 years old.
The paper reviews the author's experiences in the field of Eddy Currents over the last 35 ears, the current state of the technology and some-of the directions in which its future might lie.
Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00
Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:
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