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Electricity and magnetism run nearly everything we plug in
or turn on. Although it’s something we take for granted, it has taken hundreds of years of experimentation and research to
reach the point where we flick a switch and the lights go on.
Ancient Greeks knew rubbing amber generated static
electricity, but they didn’t know why. The Greek word for amber is elektron.
People knew about electricity for a long
time. Ancient Greeks noticed that if they rubbed a piece of amber, feathers would stick to it. You’ve experienced a similar
thing if you’ve ever had your hair stick up straight after you combed it, or had your socks stick together when you removed
them from the drier. This is called static electricity, but back then nobody knew how to explain it or what to do with it.
Experiments using friction to generate static electricity led to machines that could produce large amounts of static
electricity on demand. In 1660 German Otto von Guericke made the first electrostatic generator with a ball of sulfur and some
cloth. The ball symbolized the earth, and he believed that this little replica of the earth would shed part of its electric
“soul” when rubbed. It worked, and now scientists could study electric shocks and sparks whenever they wanted.
A
Leyden jar from about the 1910s. Courtesy: David Rickert.
As scientists continued to study electricity, they began thinking
of it as an invisible fluid and tried to capture and store it. One of the first to do this was Pieter van Musschenbroek of
Leyden, Holland. In 1746 he wrapped a water-filled jar with metal foil and discovered that this simple device could store
the energy produced by an electrostatic generator. This device became known as the Leyden jar.
Leyden jars were very
important in other people’s experiments, such as Benjamin Franklin’s famous kite experiment. Many people suspected that lightning
and static electricity were the same thing, since both crackled and produced bright sparks. In 1752 Franklin attached a key
to a kite and flew it in a storm-threatened sky. (NOTE that Franklin did not fly a kite in an actual storm. NEVER do that!)
When a thundercloud moved by, the key sparked. This spark charged the Leyden jars and proved that lightning was really electricity.
Like many experimenters and scientists Franklin used one discovery to make another.
Franklin was not the only scientist
inspired to conduct experiments with electricity. In the 1780s, the Italian scientist Luigi Galvani made a dead frog’s leg
move by by means of an electric current. Galvani called this “animal electricity.” He thought that the wet animal tissue generated
electricity when it came in contact with metal probes. He even suggested that the soul was actually electricity.
Alessandro Volta’s “pile.” Courtesy: Tempio Voltiano.
Fellow Italian Alessandro Volta was skeptical of Galvani’s conclusions.
In 1799 he discovered that it wasn’t animal tissue alone producing the electric current at all. Volta believed that the current
was actually caused by the interaction of water and chemicals in the animal tissue with the metal probes. Volta stacked metal
disks separated by layers of cardboard soaked in salt water. This so-called voltaic pile produced an electric current without
needing to be charged like a Leyden jar. This invention is still around today, but we call it the battery. Volta’s pile was
a lot different from the batteries you put in your Discman. It was big, ugly, and messy, but it worked, making Volta the first
person to generate electricity with a chemical reaction. His work was so important that the term volt—the unit of electrical
tension or pressue—is named in his honor. As for Galvani, although he was proven wrong, his work stimulated research on electricity
and the body. That research eventually proved that nerves do carry electrical impulses, an important medical discovery.
Like
electricity, magnetism was baffling to the earliest researchers. Today manufactured magnets are common, but in earlier times
the only available magnets were rare and mysterious rocks with an unexplainable attraction for bits of iron. Explanations
of the way they work sound strange today. For example, in the 1600, English doctor William Gilbert published a book on magnetism.
He thought that these strange substances, called “lodestones,” had a soul that accounted for the attraction of a lodestone
to iron and steel. The only real use for lodestones was to make compasses, and many thought the compass needle’s movement
was in response to its attraction to the earth’s “soul.”
By 1800, after many years of study, scientists began wondering
if these two mysterious forces—electricity and magnetism—were related. In 1820 Danish physicist Hans Oersted showed that whenever
an electric current flows through a wire, it produces a magnetic field around the wire. French mathematician André-Marie Ampère
used algebra to come up with a mathematical formula to describe this relationship between electricity and magnetism. He was
one of the first to develop measuring techniques for electricity. The unit for current, the ampere, abbreviated as amp or
as A, is named in his honor.
Groundbreaking experiments in electromagnetism were conducted by British scientist
Michael Faraday. He showed that when you move a loop of a wire in a magnetic field, a little bit of current flows through
the loop for just a moment. This is called induction. Faraday constructed a different version of it called the induction ring.
In later years, engineers would use the principle of the induction ring to build electrical transformers, which are used today
in thousands of electrical and electronic devices. Faraday also invented a machine that kept a loop of wire rotating near
a magnet continuously. By touching two wires to the rotating loop, he could detect the small flow electric current. This machine
used induction to produce a flow of current as long as it was in motion, and so it was an electromagnetic generator. However,
the amount of electricity it produced was very tiny. There was still another use for induction. Faraday also created a tiny
electric motor—too small to do the work of a steam engine but still quite promising.
For thousands of years electricity
and magnetism were subjects of interest only to experimenters and scientists. Nobody thought of a practical way of using electricity
before the 1800s and it was of little interest to most people. But by Faraday’s time inventors and engineers were gearing
up to transform scientific concepts into practical machines.
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Ancient
Greeks knew rubbing amber generated static electricity, but they didn’t know why. The Greek word for amber is elektron.
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Joseph
Henry’s large horseshoe shaped electromagnet from 1831. Henry used it in experiments. Courtesy: Smithsonian Institution.
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When people realized what electricity and magnetism were they
took the first steps towards putting them to work. The very first machines hardly seem useful compared to the stuff we use
today, but 200 years ago, when the industrial revolution was getting under way in Europe, they were major breakthroughs. In
the 19th century inventors began looking for ways to use electromagnetism to run machines, which was being done at that time
by steam engines, water wheels, horses, or even people.
Joseph Henry’s large horseshoe shaped electromagnet from
1831. Henry used it in experiments. Courtesy: Smithsonian Institution.
One of the first to think about using electricity
for practical purposes was the American Joseph Henry. In 1829 he used a large battery to build a powerful electromagnet. It
was not just a scientific instrument—it could do heavy work, such as lifting hundreds of pounds of metal. With his demonstration,
Henry really began to transform electricity into something that people could use every day.
Those interested in using
electricity also found new ways to produce electric current. Inventors tried to improve the basic idea of electromagnetic
induction and used magnets to create a flow of current in wires. One of the first to invent such a machine was Frenchman Hippolyte
Pixii in 1832. Pixii’s machine generated what would today be called an alternating current. It flowed first in one direction
and then in the opposite direction. Belgian Floris Nollet improved Pixii’s electromagnetic generator around 1850, and his
design was capable of producing about 50 volts. The Nollet generator was the first to be produced in large numbers by a manufacturing
firm. They were used in electroplating, the first industrial operation to employ electricity. The Electrical Age was truly
under way.
Along with the generator came much more powerful ways to put electricity to work. A key technology
was the electric motor. By the 1800 inventors had already harnessed the power of steam to run locomotives and factory machines.
Many thought that electricity could be tapped to do the same kind of work, especially after Michael Faraday demonstrated a
tiny electric motor. In 1834 Thomas Davenport designed a motor that was strong enough to run a small printing press. He patented
the motor in 1837. But progress was slow—it wasn’t until almost 50 years later that electric motors were used commercially.
Davenport also used his motor (which was powered by batteries) to move a small railroad car around a track. Unfortunately,
commercial railroad cars were large, and so many batteries were needed that an electric railroad was not practical. But inventors
used batteries and motors to power small automobiles beginning in the 1880s. In fact, in 1900 electric automobiles outsold
gasoline-powered cars. Today, of course, most cars use gas, but electric cars continue to be developed. Since they do not
produce exhaust gas and are easier on the environment than gasoline, they continue to attract interest.
Electricity
was also put to work at an early age in the field of medicine. Just three years after the invention of the Leyden jar in 1745,
doctors in Geneva began to treat patients with electric shocks. A Swiss physician reported that victims of paralysis could
sometimes be cured by repeated shocks to their muscles. When Luigi Galvani announced the discovery of “animal electricity,”
doctors were encouraged to continue their experiments. Doctors such as Guillaume-Benjamin Duchenne, the “father of electrotherapy,”
believed that shocking people with electricity might even cure their ailments. Unfortunately, this type of medicine did not
prove effective and became much less common by the early 20th century. But there were many other uses of electricity in medicine
that succeeded. The first detection of the electric currents emanating from the brain was made in 1875, and the x-ray machine
was introduced in 1895.
However, the most successful practical early use of electricity in the 19th century was a
simple communication device called the telegraph. This new form of communication ushered in the era of electrical communication
and brought electricity to the forefront of the public’s attention.
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