Name: 電気のこと。科学のクラッシュコースの歴史 #27 (Electricity: Crash Course History of Science #27)
Uploaded: 2021-01-14T10:28:51.000Z
Duration: 12 min 33 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Like thermodynamics, the history of electrical physics has its roots in pre-industrial questions

that converged in the nineteenth century. These questions became a research paradigm,

関係詞節（制限と非制限）

driven by a whole crew of researchers… And they led to a power system that reshaped the

The study of electricity goes all the way back to antiquity. Like, for a long time,

people knew that lightning is the powerful release of energy caused when two clouds are

Much easier to study, however, was static electricity, or the electrical charge produced

by stationary friction: it waits for you to pet your cat, and then shocks you!

But for centuries, natural historians didn't really have any good ideas about how to more

For one, they had no concept of current, or electricity as a flow of electrical charge.

Current can happen either by the movement of negatively charged subatomic particles

called electrons through wires, or by the movement of charged molecules called ions.

And these people didn't know either of those things existed.

Secondly, the relationship between electricity and magnetism, which are intimately linked,

And, third, a lot of experimentation into these phenomenon basically amounted to weird

English natural philosopher Francis Hauksbee, for example, found out in the early 1700s

that spinning a glass globe produced electricity—thus creating one of the first electrical generators.

Then, in 1729, two amateur scholars named Stephen Gray and Granville Wheler discovered

that electricity could be communicated over long distances by contact.

This was an important first step toward researching currents. But mostly it was an excuse to conduct

totally ethical scientific demonstrations…

like suspending a young boy from the ceiling, charging him up, and then watching him attract

And we can't forget statesman, encyclopedist, and infamous knowitall Ben Franklin.

He witnessed one of these flying-boy demonstrations in Boston, then went home to Philadelphia

As the story goes, in 1752, he flew his kite in a storm and succeeded in “drawing off”

Inspired by this incident, he developed the lightning rod. But no real epistemic knowledge.

One of the first modern electrical physicists was Italian physician Luigi Galvani.

In the late 1700s, his assistant accidentally caused a frog's leg to twitch with a spark

Inspired by this chance observation, he conducted many freaky experiments with frogs.

After much frog-shocking, he theorized the existence of animal electricity, or the electrical

That inspired one young woman who was remarkably well informed about contemporary science:

in 1818, Mary Shelley published what would become a very famous book about a man zapped

to life by a Galvani-esque Doctor Frankenstein.

Galvani also inspired his colleague, Italian physicist and chemist Alessandro Volta, to

And Volta became a rockstar of electrical physics when he created the first practical

method of generating electricity—the first battery, known as the voltaic pile

So ThoughtBubble, let's make some sparks fly!

Volta's battery evolved from humble origins. The first iterations were made of two different

metals separated by a brine-soaked cloth or piece of cardboard.

But Volta kept improving the pile. In 1800, he stacked pairs of copper and zinc discs,

again separated by briny cloth or cardboard.

When he connected the top and bottom of the pile, it generated a steady electric current

Volta had created the first stable source of electrical current!

This type of two-metal battery fulfilled the world's scant electrical needs throughout

much of the First Industrial Revolution, until around 1870.

But no one could really explain how it worked, in part because no one had brought electricity

One of the first steps in this direction was taken in 1820 by Danish physicist and chemist

While demonstrating to his students how to heat up a wire by running an electrical current

through it, Ørsted noticed that his compass' needle kept jumping to a ninety-degree angle.

Somehow, he realized, the electrical charge and the magnetic attraction of the compass

Ørsted conducted further experiments and showed that electric currents actually produce

neatly circular magnetic fields when they flow through wires.

Later in 1820, at the Academy of Science in Paris, physicist André-Marie Ampère watched

as a friend reproduced Ørsted's electrically-messing-with-a-compass trick.

Amazed, Ampère went to work figuring out the math behind this special relationship.

He showed that two parallel, electrified wires attract each other if the currents flow in

the same direction, and repel if the currents flow in opposite directions.

Thanks Thoughtbubble. Ampère also showed that the force between the currents was inversely

proportional to the distance between them, and proportional to the intensity of the current

This became known as Ampère's law. You can watch a whole episode about that over at Crash

And he even theorized that there must be some “electrodynamic molecule” that carried

the currents of electricity and magnetism.

Ampère's insights became the foundation of the quantitative science of electromagnetism,

In 1827, Germany physicist Georg Ohm —who'd been conducting research using Volta's battery—published

between two points is directly proportional to the voltage, or potential difference, between

This can be expressed using the concept of resistance, or the difficulty of passing an

electric current through that conductor, in a really simple equation:

“I = V/R.” Current, measured in amperes, is equal to voltage, measured in volts, divided

Yep: all three scientists became standard units.

They say, in Physics the greatest honor is when your name starts to be spelled with a lower case letter.

With practical batteries and basic scientific laws, the stage was set for electricity to

become an industry—enter motors and lights.

Born to a poor family in Newington Butts, London, Michael Faraday became obsessed with

electricity and chemistry at a young age.

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電気のこと。科学のクラッシュコースの歴史 #27 (Electricity: Crash Course History of Science #27)

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