- How did Michael Faraday make electricity with magnets?
And hey, how does anyone make electricity with magnets?
And what does that have to do with the
creation of the idea of magnetic fields?
Well, watch this video and find out ready. Let's go.
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- In 1826, an English scientist named Michael Faraday
read than another Englishman named William Sturgeon
had made a pretty strong magnet by wrapping wire
around the iron bar and putting current in the wire.
Because electricity makes the bar act like a magnet,
Sturgeon's creation is logically called an electromagnet.
Sturgeon had used an iron bar that was covered in
lacquer and bare wire.
Because of this, he had to be careful that
the wires didn't touch or the electricity would just
short circuit across the wires, instead of through them.
Faraday had a little, six inch iron ring that wasn't coded.
He decided to wrap the wires with cloth to insulate them
instead of coding the iron ring.
In this way, he could wrap the wires very closely together
and make a much stronger electromagnet.
Because this iron was a ring,
Faraday wrapped two separate coils,
one for the left side of the ring, and one for the right.
It looks like a strange artifact from a mommy's crypt.
Faraday used to keep this ring in his pocket while
he did other research.
He was sure it would be useful somehow,
he just didn't know how.
Then in August of 1831, he took a professional risk.
Faraday quit his government research job that he hated
and decided to branch out on his own.
What Faraday wanted to do, was study electricity and
magnetism.
Specifically, He was determined to create electricity
with a magnet.
After all, It had been 11 years since a Danish man
named Hans Christian Oersted had shown that
electricity pushes magnets.
It seemed logical that magnets must affect electricity.
For many years Faraday had been tinkering with magnets
and electricity, but to no avail.
He wondered if the magnet wasn't strong enough.
For that reason, Faraday day took out his
little ring from his pocket.
He decided to use one side of the ring as his magnet,
and the other side as his tester, to see if he could create
current without directly connecting to a battery.
He put a compass under the tester wire to see if
it had any current.
When Faraday connected the battery to the first coil
an amazing thing happened.
The magnet next to the second coil twitched, then nothing.
When he cut off the current,
the magnet twitched again in the other direction,
then nothing again.
Faraday repeated this experiment many times
and he found he created current in the second coil,
when the first one was charging up or discharging,
but never when it was flowing steadily,
even when it had incredibly large current.
In other words, an electromagnet only creates current
in another coil when the magnetic field was changing.
If its strength is steady, nothing happens.
Faraday wrote to a friend about his experiment.
Quote "I'm busy just now again on electromagnetism.
And I think I've got hold of a good thing, but I can't say.
It may be a weed instead of a fish.
But after after all my labor, I may at last pull up,"
Faraday had managed to create electricity with electricity,
but he still hadn't managed to create electricity
with a magnet.
After several attempts that were too subtle to be observed,
Faraday pushed a very strong magnet into a coiled wire
and retrieved it again.
When the magnet was moving, the compass moved too.
Here was the fish that Faraday was hoping to catch.
He had briefly created electricity with magnets.
He had another device at his disposal.
The Royal Institution where Faraday worked
had a giant magnet, actually 437 magnets stuck together,
that Faraday could play with.
Faraday placed an iron bar on this great magnet,
thereby making the iron bar a magnet too.
When he moved the coil towards and away from the bar,
he created current in the coil.
However, even with this very strong magnet,
no current was detected when the coil was still.
Let's review Faraday's discoveries.
He created current in a wire if he moved the coil
towards or away from a strong magnet.
I he moved a magnet towards or away from a coil of wire,
or if he increased or decreased the magnetism of an
electromagnet near a coil of wire.
Faraday, needed a way to describe this new phenomenon.
He was a visual thinker with no math skills.
So he began imagining magnetic curves emanating
from bar magnets, current carrying wires,
and electromagnets.
For centuries, people had noticed that if you sprinkle
iron filings around a bar magnet, it creates patterns.
Faraday said that the iron filings
were lining up with these quote
"lines of magnetic forces that were always present around
the magnets and around current carrying wire.
The iron filings just made them visible."
In this way Faraday came up with the idea of magnetic fields
way back in 1831.
Faraday said that current was created or induced
when the lines of magnetic force were broken or cut
by the coil of wire.
Think about pushing the bar magnet in to a coil of wire.
As you push the magnet, the magnetic field lines
pass through the coil and induce current.
Faraday felt it was this disturbance of the force,
not to get too Star Wars about it,
that created the current in the coil.
Strangely enough, that is the theory we believe today.
Faraday realized that the current he produced was in spurts.
He wondered if he could make continuous current,
like a battery though.
In this quest, he was helped by
something called Arago's disk.
See, nine years earlier, a swashbuckling Frenchman
named Francois Arago had noticed that
if a copper disc was rotated near compass magnet,
the compass magnet would turn too.
Faraday decided that Arago's disk worked
because moving the wheel moved parts of the wheel closer
and further from the magnet,
which induced current in the wheel.
That induced current created a magnetic field that
pushed the original magnet.
Faraday decided to test his hypothesis
with the giant magnet at his disposal.
He added metal to his large magnet to make it
into a U shaped magnet.
He then placed the copper disk so that it could
spin between the poles,
and connected the disc with wires to a meter,
to measure the current.
When he spun the wheel, the needle turned
and stayed constant.
Faraday had used motion to get constant current.
In fact, he had invented the first electric generator.`
The scientific community was very impressed
with his findings, and especially with his solution
to the mystery of a Arago's disk.
Faraday himself felt particularly satisfied
to have succeeded without using math.
A subject he didn't know.
Faraday published his work in 1832.
It was so popular that the prime minister of England
dropped by to see Faraday's generator firsthand.
When the prime minister asked Faraday about its uses,
Faraday, supposedly replied, quote:
"I know not, but I wager one day
that the government will tax it."
Although the generator Faraday made
was useful for demonstrations,
it wouldn't produce very much useful current.
That's because when you spun the disk,
it would create current in the disc called edicurrent,
that would get in the way of producing large current
in the wires.
In fact, it would take another 30 years
before a cast of characters managed to make
a useful generator.
And that story is next time,
on the secret history of electricity.
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