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Electromagnetism (continued)
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and magnetostatic fields. From the 1820s to the 1850s, Michael
Faraday discovered the law of induction, the electromagnetic
field, and other principles. He also invented the electric motor
and the electric generator, thereby opening the door for the
widespread application of electromagnetism.
In 1861, James Clerk Maxwell (Fig. 3) organized the laws of
electromagnetism into one complete set. In doing so, he
predicted the existence of electromagnetic waves theoretically.
Heinrich Hertz performed experiments with radio waves in
the 1880s that confirmed Maxwell's prediction. Hertz's find-
ings led to the theoretical unification of electromagnetism and
optics. Near the end of the nineteenth century, engineers such
as Thomas Edison and Nikola Tesla transformed society with
a flood of electromagnetic inventions. Their teams installed
electric power plants and power grids in major cities at a frantic
pace. By the dawn of the twentieth century, electric appliances
and devices were beginning to pervade many facets of modern
society.
Throughout the twentieth century, various scientists such as
Albert Einstein, Werner Heisenberg, and Paul Dirac established
the quantum nature of
electromagnetism. Cur-
rently, the most accurate
theory of electromagnetism
is quantum electrodynamics
(QED), which is an integral
part of the standard model
of particle physics. In the
second half of the twentieth
century, the detailed under-
standing of the quantum
nature of electromagne-
tism led to semiconductor
devices and the birth of the
Digital Age. Unsolved prob-
lems in electromagnetism
include the existence of mag-
netic charge and the theoretical unification of electromagne-
tism with the strong nuclear interaction, as well as with gravity.
Electromagnetism and the weak nuclear force were unified into
the so-called electroweak interaction in the 1970s.
Fig. 3: A portrait of James Clerk Maxwell from
the late nineteenth century.
