- To understand the electromagnet,
it's helpful to take a moment to learn a little bit
about its inventor, William Sturgeon.
William's life was dramatic and inspirational,
although his sideburns and hair were a little bit,
I think, bizarre.
Anyway, take a moment to learn how a retired soldier
and bookmaker invented the electromagnet
and how the electromagnet works, ready?
Let's go.
♪ Electricity, electricity ♪
- William Sturgeon was born in 1783 in Northern England
to a poor shoemaker who treated him badly.
When he was 10, his mother died and a few years later,
his father basically sold him to another shoemaker,
who also treated him cruelly.
And according to Sturgeon, he lived a life of, quote,
"slavish drudgery."
When he was 19 years old, he escaped by joining the army.
The army was good for Sturgeon.
He found that the officers, in particular, were appreciative
of the skill of fixing things, especially their shoes.
He would also entertain the officers and fellow soldiers
with amateur science demonstrations that he made himself.
He then traded his skills for lighter duties
and to borrow books from the officers.
Remember, at this time in England,
there were no free libraries
and books were prohibitively expensive.
In this way, he actually taught himself math,
Greek, Latin, French, German, Italian,
optics, and lithography.
After 18 years in the army,
Sturgeon retired and moved
to the Woolwich district of London.
His plan was to start a shoe store.
For that reason,
he contacted some of the officers he knew from the military.
However, many of them were interested
in the latest development in science
and asked Sturgeon for help with their scientific devices,
as well as for their shoes.
It was fortunate timing because in that same year,
Hans Christian Oersted in Denmark had discovered
the current in a wire moves the magnet in a compass.
One of the things that was intriguing
about Oersted's experiment was that Oersted discovered
that when the current went down a wire,
it would force magnets to point
in a circle around that wire.
For that reason, Oersted incorrectly deduced
that the current wasn't really going down the wire,
but instead was spiraling around inside the wire.
In France, a man named Ampere read Oersted's paper
and started to do a series of experiments
about electricity and magnetism.
For example, Ampere determined the two parallel wires
with current in it would feel
an attractive force between them.
Ampere's experiments were so influential
that current is measured in amps in his honor.
One day, Ampere was thinking about Oersted's theory,
that current spiraled inside the wire,
and wondered what would happen
if the wire itself was spiraling.
Ampere thus coiled up a wire in a helix
and studied the magnetism created by the current.
The next year, a young Englishman named Michael Faraday
published his theory that we still believe today.
The electricity is really flowing
straight down the wire and improbably is it seems,
somehow creating a circular force field around it.
Faraday also stated that the force fields
from many wires worked with each other
in what Faraday called compound action.
For example, Faraday interpreted Ampere's experiment
with two wires to feel an attractive force
as the compound action of the magnetic fields
from the wires supporting each other.
Faraday also wrote that Ampere's spiral coil
also demonstrated how the fields were additive
from parallel wires,
as if you look at a coil,
it is composed of many parallel wires.
Faraday also noted that a coil of wire
with current in it acts identically to a bar magnet,
albeit it a weak one.
Let's go back to William Sturgeon.
By 1824, Sturgeon's friend had helped him get a job
giving science demonstrations to a military academy.
So he had the time and money to read Faraday's
and Ampere's papers and try to recreate their experiments
and even bump them up a notch.
One day, he was recreating Ampere's coil
and happened to wrap a coil of wire around an iron bar.
To his surprise, the iron bar amplified
the magnetic effects of the coil.
Because the electricity in the wire
makes the iron act like a magnet,
this object is called an electromagnet.
Let's take a moment to talk about a magnet
and an electromagnet.
A permanent magnet always contains the north and the south.
A north and a north will repel,
a south in the south will repel,
and the north and the south will attract.
Permanent magnets also attract certain metals
that are not magnet.
For example, if a magnet is placed near a paperclip,
the paperclip will be attracted to the magnet.
This is because the paperclip is made of steel
and steel is composed of little magnets,
or magnetic domains, that are randomly arranged.
When the paperclip is near a magnet,
the little magnetic domains line up,
making the paperclip into a temporary magnet,
where the north of the paperclip
is attracted to the south of the magnet.
You know an object is a magnet if it aligns
and attracts a metal paperclip.
Now let's talk about the electromagnet.
An electromagnet is a coil of wire wrapped
around an iron or steel bar.
Without current, the bar will not attract paperclips
or act like a magnet at all.
However, if current runs through the wire,
then the magnetic fields in the wire align
the magnetic domains in the iron or steel bar
and make it act like a magnet with a north and a south.
The bigger the current, the stronger the magnet.
Once you disconnect the battery,
the iron or steel basically stops being a magnet.
In 1826, Sturgeon found that if he wrapped wire
around a U-shaped iron bar,
he could create a U-shaped magnet.
It was so strong that even with the weak batteries
at the time, with just a few turns of coil,
an electromagnet could hold nine pounds of weight
and then drop it dramatically
when the current was disconnected.
Sturgeon was awarded a silver metal for this discovery,
as well as 30 guineas.
At the time, everyone thought the big advantage
of electromagnets was to make theatrical demonstrations,
and they certainly were theatrical.
However, it turns out that a magnet
that you can control electrically is far more useful
and important than anyone knew at the time.
In fact, the electromagnet was vital
for the discovery of a whole host of electric devices,
like the telephone, the electric generator,
the radio, the x-ray machine,
and the television, to name just a few.
One of the first important devices
that used Sturgeon's electromagnet
was the electromagnetic telegraph.
See, in 1827, Sturgeon's paper made it all the way
to the backwoods of New York State,
where a bored math teacher named Joseph Henry read it
and invented the telegraph.
Then, a racist egoist named Samuel Morse, as in Morse Code,
stole the ideas and the fame and money.
And that crazy story starts next time
on The Secret History of Electricity.
♪ Electricity, electricity ♪
- Thanks for watching my video.
Please remember to give it a nice thumbs up,
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And I'll see you next time
on The Secret History of Electricity.
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Thanks, have a good day.
(upbeat music)