121
See also: Alessandro Volta 90–95 ■ Hans Christian Ørsted 120 ■
James Clerk Maxwell 180–85B
ritish scientist Michael
Faraday’s discovery of
the principles of both the
electric motor and the electric
generator paved the way for the
electrical revolution that would
transform the modern world,
bringing everything from lightbulbs
to telecommunications. Faraday
himself foresaw the value of
his discoveries—and the tax
revenues they could generate
for government.
In 1821, a few months after
hearing of Hans Christian Ørsted’s
discovery of the link between
electricity and magnetism, Faraday
demonstrated how a magnet will
move around an electric wire, and
an electric wire will move around a
magnet. The electric wire produces
a circular magnetic field around it,
which generates a tangential force
on the magnet, producing circular
motion. This is the principle behind
the electric motor. A spinning
motion is set up by alternating the
direction of the current, which
alternates the direction of the
magnetic field in the wire.Generating electricity
Ten years later, Faraday made an
even more important discovery—
that a moving magnetic field can
create or “induce” a current of
electricity. This discovery—which
was also made independently by
the US physicist Joseph Henry
around the same time—is the
basis for generating all electricity.
Electromagnetic induction converts
the kinetic energy in a spinning
turbine into electrical current. ■A CENTURY OF PROGRESS
ONE DAY, SIR,
YOU MAY TAX IT
MICHAEL FARADAY (1791–1867)
IN CONTEXT
BRANCH
Physics
BEFORE
1800 Alessandro Volta invents
the first electric battery.
1820 Hans Christian Ørsted
discovers that electricity
creates a magnetic field.
1820 André-Marie Ampère
formulates a mathematical
theory of electromagnetism.
AFTER
1830 Joseph Henry creates the
first powerful electromagnet.
1845 Faraday demonstrates
the link between light and
electromagnetism.
1878 Designed by Sigmund
Schuckert, the first steam-
driven power station generates
electricity for the Linderhof
Palace in Bavaria, Germany.
1882 US inventor Thomas
Edison builds a power station
to power electric lighting in
Manhattan, New York City.
In Faraday’s apparatus for showing
electromagnetic induction, a current
flows through the small magnetic coil,
which is moved in and out of the large
coil, inducing a current in it.