Electrostatic forces and magnetic forces
have both been discovered over thousands
of years ago. These seemingly unrelated
interactions have one major similarity:
that is they both are a type of
attractive or repulsive force. Our
current understanding of electric forces
is through electric fields which we've
just covered. So naturally our current
understanding of magnetic forces is
through magnetic fields. While humanity
has been aware of electric and magnetic
forces for a long time, not much progress
in understanding these forces was made
until the 19th century. Voters Pile gave
us a reliable way of producing
electricity at the beginning of the 19th
century. In 1800, this opened up the door
to test for the relationship between
electricity and magnetism.
However the link proved to be elusive. It
took twenty years and many experiments
until an accidental discovery finally
unified electricity and magnetism into
electromagnetism. This accidental
discovery was made by Hans Christian
on the 21st of April in 1820. While
setting up an experiment for an evening
lecture, he noticed the deflection of a
compass needle when an electric current
was run through a wire. Prior to this
discovery, compass needles have only been
known to react to other magnetized
objects. Running a current through a wire
made the needle turn, indicating that
there was a magnetic field due to the
electric current. We know that charges
generate an electric field and as this
discovery can be summarized by moving
charges generate a magnetic field. A
current is comprised of lots of moving
charges, so we generally say a current
creates a magnetic field.
Hence Christian demonstrated that
a compass points tangential to the
magnetic field at every point. And that
it will point in opposite directions
when placed on opposing sides of current,
which is a fancy way of saying that the
magnetic field is circular. Well, look at
this magnetic field in later videos.
After this revelation, Ted left this
discovery for a few months before
returning to investigated further. His
notes on how exactly he made
discovery was also incomplete, which has
left an envelope in scientific history.
He also never quantified the strength of
the magnetic field around the current.
Due to these events, that is mostly
forgotten to history these days with
names like Ampere and Maxwell, that are
much more synonymous with
electromagnetism.
