- What was Orsted's experiment?
Well it was incredibly simple.
He just put a compass under a wire.
Wait, why is that important?
And why is that weird?
Sounds pretty normal to me.
Well I'll explain in the video.
Ready? Let's go.
(theme song)
♪ Electricity, E-lectricity ♪
♪ Electricity, E-lectriciy ♪
This Story begins in 1600.
That's when an English doctor
determined that static electricity
is completely separate from magnetism.
Flash forward 200 years
when an Italian named Allesandra Volta invented the battery.
Suddenly there was renewed interest in finding a connection
between electricity and magnetism.
It seemed logical.
Magnets always have a north and the south
and batteries always have a positive and a negative.
Stil, nothing.
This brings us to Denmark and a philosopher and scientist
named Hans Christian Orsted
who was a big fan of the philosophy of Emmanuel Conte.
To Orsted, Contes philosophy meant
that everything in nature was intertwined.
So the forces and physics should also be connected.
He was determined to quote prove from empirical science
how the laws of nature form a rational whole
and how nature itself is a revelation of reason
Beginning in 1806, Orsted did everything he could
to see if magnets could have an effect on electricity
or vice versa.
For 14 years, a whole bunch of nothing.
Then, in the spring of 1820
Orsted put a compass underneath a wire
and found that the compass needle turned
when the current was running through the wire.
Now Orsted knew that a compass
is just a small magnet on a pivot.
That is why you can make a compass needle move
by placing a permanent magnet near it.
So if the current in the wire
moved the magnet in the compass
that means electrical current creates a magnetic force.
Not in the battery, but in the current in the wire.
Let's go into a little more detail
about what or Orsted did.
Orsted used a battery
that was composed of copper and zinc rods in an acid bath.
He then placed the compass under a wire
in the closed circuit and voila
the magnet and compass moved.
Strangely, the magnet did not move to point with the wire
towards the wire, or away from the wire.
No, the magnet moved to point in a circle around the wire.
This is why the experiment is so strange.
The current flows through the wire
and the magnet points around the wire.
Think about it.
There are no other forces that work like this.
Gravity pulls you towards the center of mass.
Magnets and static electricity either pull you
or push you away.
Even directly pushing or pulling
is either towards or away from
the person pushing or pulling.
But compasses feel of course
pushing them into a circle around the wire.
No wonder it took Orsted 14 years to discover.
He was putting his compass in the wrong orientation.
The other thing that was
and is odd about this experiment
is that static charges do not move a magnet
only moving charges do.
Okay. That's strange, but why is that important?
First, it linked electricity and magnetism
which is fundamental difference
in our understanding of both electricity and magnetism.
Second, the fact that an external compass moves
if there's a current in a wire
made it possible to study electricity and magnetism
more systematically
which led to a profusion of new equations and theories.
- Months after Orsted published his account
a German scientist wrapped the wire multiple times
around the compass
to increase the force on the compass
and made the first calibrated machine
to measure the strength of current.
In 1825, another German scientist named Georg Ohm
used this device to determine the relationship between
current and the properties of the materials
that the current runs through.
Includint its temperature.
Ohm then created the idea of resistance
which is measured in ohms in his honor.
In fact, many of the electrical equations we use today
were born in this time period.
Third, the relationship between electricity and magnetism
started an avalanche of practical electrical devices.
Before Orsted, batteries were only used for three things.
One, to give small electric shocks
two, to electrically isolate chemicals
and three, to create a bright light
that required too many batteries to be practical.
Within a dozen years of or Orsted's discovery
the following devices were invented.
The Ammeter, the motor, the electromagnet, the transformer
the generator, and even the first practical telegraph.
- In fact, you can trace back almost all
of our electrical devices
to this single discovery.
It is a big deal.
So what did Orsted think of his discovery?
Well, he knew it was important.
In fact, he had discovered it a month before he
published his findings
but the battery was a little weak.
So he repeated it with a stronger battery.
Quote, "considering the importance of the subject".
Unfortunately, many people who read this
thought that Orsted's original experiment was an accident.
Therefore, instead of being lauded
for fulfilling his 14 year quest
he is most often rumored to have done it by chance.
Also, Orsted, like many scientists at the time
was disturbed by the fact that the current through the wire
and the magnetic force goes in a circle around the wire.
It seemed totally illogical to people used to Newton's laws.
To solve his problem
he decided that the electricity was really not moving
straight down the wire at all.
Instead, the electricity was spiraling down the wire
and dragging the magnets in a spiral direction too.
In England, a lowly and uneducated chemical assistant
named Michael Faraday
attempted to systematically study Orsted's theory
of the spiraling current.
Instead, he found that the current wasn't spiraling
it was going straight down the wire
but it was creating a circular force field on the magnets.
In return, he also theorized
that magnets create a circular force field on current.
This was to revolutionize
the study of electricity and magnetism
and lead to the theories
of magnetic fields and electric fields.
But why did anyone listen to a lowly chemical assistant?
Well it turned out the Faraday
had the experiments to prove his theories.
How Michael Faraday created the first electric motor
and infuriated his mentor in the process
is next time on the secret history of electricity.
(theme song)
♪ Electricity, E-lectricity ♪
Thanks for watching my video.
Please remember to give it a nice thumbs up.
Also check out the videos on how the battery was invented
and how Michael Faraday became a lowly chemical assistant
instead of a lowly bookbinders apprentice.
Also, make sure to check out the next one
about how Faraday invented the first electric motor.
It's going to be cool.
Remember to join my YouTube channel, Kathy Loves Physics.
My Facebook page, Kathy loves Physics
or my website www.kathylovesphysics.com.
Okay. Have a nice day.