Magnet Milestones: The Discovery of Electromagnetism
By Amy Mast
Some discoveries are so big that it takes several of an
era's best minds working together to achieve them. For
example, today, scientists all over the world are working
both together and competitively to figure out how and why
superconductivity works, and how it can be applied to use
energy more efficiently.
Almost 200 years ago, across several countries and without an
e-mail inbox in sight, scientists were working this same way to
explore the mysterious relationship between electricity and
magnetism.
Ørsted: The explorer
Hans Christian Ørsted.
If you had some friends over
and accidentally made a
scientific discovery, you'd
probably show it to them
and tell them all about it,
right?
Not Hans Christian Ørsted
of Denmark. In the
fall of 1820, he invited
some colleagues over to
show them the way metal
could conduct an electrical
current. When he fired up
the current, he noticed the
needle on a nearby
compass – on hand for a
different demonstration
– moved. No one had yet
observed a relationship
between electricity and
magnetism, and Ørsted was
stunned. He kept the finding
secret for three months while
he tried to figure out how
and why his demonstration
had affected the magnetic
field of the compass.
Up until this point, only
lodestones (naturally
occurring stones with a
high concentration of iron)
and iron itself were known
to give off a magnetic field.
Ørsted replicated his finding
and studied it intently, but
couldn't come up with
an explanation for the
phenomenon on his own.
He ended up publishing
his discovery with no
explanation.
Ampère: The explainer
André-Marie Ampère.
The scientific community of
the day went crazy trying to
explain the phenomenon;
over a hundred papers were
published on the subject in
the following seven years.
At the head of the pack
was French physicist and
mathematics professor
André-Marie Ampère.
Only a week after he learned
of Ørsted's work, Ampère
presented his own findings.
He demonstrated that when
two wires were placed
parallel to one another,
both carrying an electric
current, they'd either be
attracted to or repulsed by
each other depending on
which directions the currents
were traveling. If both
currents moved in the same
direction, the wires would
be attracted to one another.
If the currents were moving
in opposite directions, the
wires repelled one another
instead.
It sounds simple, but
this finding proved the
spark for the study of
electromagnetism as a field
of interest, and became
one of the foundations of
modern physics. Ampère also
figured out how to quantify,
or measure, the intensity
of the interaction between
different electromagnetic
currents, and how to nail
down the relationship
between electricity and
magnetism with an equation
known as Ampère's Law.
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