McGill University, Montréal, Quebec, Canada
Branko D. Popovićy
University of Belgrade, Belgrade, Yugoslavia
University of Colorado, Boulder, Colorado, U.S.A.
To the loving memory of our father, professor, and coauthor. We hope that he would have
agreed with the changes we have made after his last edits.
— Milica and Zoya Popović
In 1831 Michael Faraday performed experiments to check whether current is produced in
a closed wire loop placed near a magnet, in analogy to dc currents producing magnetic
fields. His experiment showed that this could not be done, but Faraday realized that a
time-varying current in the loop was obtained while the magnet was being moved toward it or
away from it. The law he formulated is known as Faraday’s law of electromagnetic
induction. It is perhaps the most important law of electromagnetism. Without it there
would be no electricity from rotating generators, no telephone, no radio and television, no
magnetic memories, to mention but a few applications.
The phenomenon of electromagnetic induction has a simple physical interpretation.
Two charged particles (‘‘charges’’) at rest act on each other with a force given by
Coulomb’s law. Two charges moving with uniform velocities act on each other with an
additional force, the magnetic force. If a particle is accelerated, there is another additional
force that it exerts on other charged particles, stationary or moving. As in the case of the
magnetic force, if only a pair of charges is considered, this additional force is much smaller
than Coulomb’s force. However, time-varying currents in conductors involve a vast
number of accelerated charges, and produce effects significant enough to be easily
This additional force is of the same form as the electric force (F ¼ QE). However,
other properties of the electric field vector, E in this case, are different from those of the
Copyright © 2004 by Marcel Dekker, Inc.
electric field vector of stati