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History of electricity

by Chris Woodford . Last updated: December 3, 2021.

I f the future's electric, why isn't the past? Think a little bit about that simple-sounding question and you'll understand what science is all about and why it matters so much to humankind. Consider this: the ancient Greeks knew some basic things about electricity over 2500 years ago, yet they didn't have electric cookers or fridges , computers or vacuum cleaners . How come? Electricity is just the same as it was back then: it works in exactly the same way. What's changed is that we understand how it works now and we've figured out effective ways to use it for our own ends. In other words, science (how we understand the world) has gradually helped us to produce effective technology (how we harness scientific ideas for human benefit). The steadily advancing science of electricity has led to all kinds of electrical technologies that we can no longer live without. It's been an incredible achievement, but where and how did it begin? Let's take a closer look!

Photo: A statue of Thales of Miletus gripping the discovery for which he's best known: electricity. Photo of a statue by Louis St. Gaudens at Union Station, Washington, DC. Credit: Photographs in the Carol M. Highsmith Archive, courtesy of Library of Congress , Prints and Photographs Division.

Ancient sparks

Way back in 600BCE, a Greek mathematician and philosopher named Thales (c.624–546BCE), who lived in the city of Miletus (now in Turkey), kicked off our story when he discovered the basic principle of static electricity (electricity that builds up in one place). As he rubbed a rod made of amber (a fossilized tree resin), he found he could use it to pick up other light objects, such as bits of feathers. (You've probably done a similar experiment rubbing a ruler or a balloon and using it to pick up pieces of paper.)

Before Thales came along, people might well have explained something like this as magic: ancient people didn't reason things out scientifically the way we do today. Their explanations were often a muddled mixture of magic, superstition, folklore (stories), and religion. [3] Thales is often called the world's first scientist, because he was one of the very first people who tried to find sensible, rational explanations for things. His explanations weren't always correct (he thought everything in the Universe was ultimately made of water and believed Earth was a flat disc), but they were the best logical deductions he could make from his observations of the world—and, in that sense, they were scientific. [4]

Photo: "Aristotle" pictured at the National Academy of Sciences, Washington, D.C. Credit: Photographs in the Carol M. Highsmith Archive, courtesy of Library of Congress , Prints and Photographs Division.

The logical, scientific ways of doing things we rely on today were developed by later Greeks such as Aristotle (348–322BCE) and Archimedes (287–212BCE), who built on Thales' work, and Islamic scholars such as Alhazen (965–1040CE), who gave us the scientific method : coming up with a tentative explanation for something (a hypothesis), which is then tested through experiments to make a more robust explanation (a theory). Important though these people were, electricity (as we know it today) didn't figure in their thinking. They had little conception of how useful it could be—or what it would eventually lead to. They were more concerned with astronomy, mathematics, matter, and optics (how light works). Science might have been in its advent, but electricity was still just a "magical" curiosity—of very little practical use.

Positive and negative

Artwork: William Gilbert gave us our word for "electricity." Photograph courtesy of the Wellcome Collection published under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence.

Incredibly, the scientific study of electricity didn't really advance any further for a full 2000 years after Thales' original discovery. But around 1600CE, Englishman William Gilbert (1544–1603), a physician to the English Queen Elizabeth I, started to probe it further. Gilbert was the person who coined the Latin term "electricus" (a word meaning "like amber," reflecting Thales' original discovery) and he believed electricity was caused by a fluid called "effluvium" that could move from place to place. This was an important insight because it was the first real suggestion that electricity could form what we now call a current, as well as remain static (in one place). Although Gilbert is much better known for his work on magnetism (he made the important deduction that Earth behaves like a giant magnet), and compared it with electricity, he didn't unite the two things in a single theory. If he'd done so, he probably would have gone down in history as one of the greatest physicists of all time. (As we'll see later, the person who finally achieved that, James Clerk Maxwell, is celebrated in exactly that way.)

Artwork: "Experiments and Observations Tending to Illustrate the Nature and Properties of Electricity": The cover of William Watson's book of electrical research.

It was now becoming clear that there was much more to electricity than the ancients had realized. In 1733/4, almost 150 years after Gilbert's death, a French physicist named Charles du Fay (1698–1739) made the next important breakthrough when his experiments revealed that static electricity could come in two different (opposite) flavors, which he named "vitreous" and "resinous." If you rubbed some objects, they gained one kind of electricity; if you rubbed others, they gained the opposite kind. Just as two "like" magnets (two north poles or two south poles) will repel, so two objects with "like charges" of electricity will also repel, while objects with unlike charges (like magnets of opposite poles) will attract. Although we now know this idea is correct, back in the 18th century, such a convoluted explanation sounded wrong to some people. Why should there be two kinds of electricity? Didn't it flout a basic scientific principle called Occam's razor —the idea that explanations should be as simple as possible? Englishman Sir William Watson (1715–1787) thought there was just one kind of electricity, with an ingenious explanation much more like our modern view: if we have too much electric charge, it seems like one kind of electricity; if too little, the other kind. Watson gave us the concept of electric circuits (closed paths around which charge flows) and made an important distinction between conductors and insulators. He was also one of the first to show that electricity could zip down very long wires, and his other experiments included passing electricity through lines of several people to give them surprising electric shocks.

Photo: A museum exhibit at Independence National Historical Park in Philadelphia, Pennsylvania, illustrating Benjamin Franklin's highly dangerous attempt to catch electricity in a thunderstorm. Credit: Carol M. Highsmith's America Project in the Carol M. Highsmith Archive, courtesy of Library of Congress , Prints and Photographs Division.

Two decades later, the question of how many kinds of electricity there were was effectively settled by Watson's contemporary, the American polymath Benjamin Franklin (1706–1790). Printer, journalist, inventor, statesman, scientist and more, he made all sorts of contributions to 18th-century American life. One of his most important achievements was confirming that there was a single "electric fluid," giving rise to the two "kinds" of electricity, which he named (as we still do today) "positive" and "negative." Like Watson, Franklin helped to tease out the mystery between static and current electricity. In his most famous (and indeed most dangerous) experiment, he flew a kite in a thunderstorm with a metal key attached to it by a long string. The basic idea was to catch electrical energy in the clouds (static electricity) from a lightning strike (current electricity), which he hoped would travel down the string to the key (more current electricity). Fortunately, lightning didn't strike the kite, which might well have killed Franklin, but he was able to detect charges and sparks, so confirming his ideas. DON'T try anything like this at home! [5]

“ And when the rain has wet the kite and twine, so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle. ” Benjamin Franklin, 1752 [12]

Franklin's electrical research marked a new milestone and hinted of much more to come, because it suggested electricity could be captured and stored as a form of energy. But electricity turned out to be even more useful when people discovered how it could exert a force. That was demonstrated by Frenchman Charles Augustin de Coulomb (1736–1806), who charged up two small spheres with positive electricity and then measured the (repulsive) force as they pushed away from one another (repelling the same way as two magnets with like charges). Coulomb found that the force between charges depended not just on their size but also on the distance between them—something now known as Coulomb's law. (The basic unit of electric charge is also named the Coulomb in his honor.)

Electrical experiments were still hampered by the sheer difficulty of making and storing electricity, which, at this time, essentially relied on rubbing things to build up a good static charge. The study of electricity really advanced when a group of European scientists devised ways of storing electrical charges in glass jars with separate pieces of metal attached to the inside and outside surfaces—devices known as Leyden jars, which were the first effective capacitors (charge-storing devices). Developed independently in the 1740s by German Ewald Georg von Kleist and Pieter van Musschenbroek (of the city of Leyden, hence the name), they offered a much more convenient way of studying electricity.

Photo: Electrical research as it was in the early 18th century: A pair of glass Leyden jars (center) with their electrical connections to an electricity generating machine (right). Oil painting by Paul Lelong c.1820 courtesy of the Wellcome Collection published under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence.

Animal magic

Ever since Thales' original discovery, scientists knew that static electricity could be made by rubbing things, but no-one knew exactly why this was so or where the electricity ultimately came from. In the late 18th century, Italian biologist Luigi Galvani (1737–1798) found he could make electricity in a completely different—and totally unexpected—way: using the legs of a dead frog. In his most famous experiment of all, when he pushed brass hooks into a frog's legs and hung them from an iron post, he saw the legs twitch from time to time as electricity flowed through them. That led him to think that living things like frogs contained something he called "animal electricity," which the metals were somehow releasing.

Artwork: Luigi Galvani believed he'd discovered "animal electricity" when he hung a frog's legs from a metal hook (left) and watched them twitching. Illustration courtesy of US Library of Congress .

In fact, as another Italian, physicist Alessandro Volta (1745–1827) soon discovered, Galvani had leaped to the wrong conclusion. The twitching frog was merely the current detector, not the source of the current. The important thing, as Volta discovered when he experimented with all sorts of different materials, was "the difference in the metals." What was really happening was that the two different metals, connected through the moist, fleshy, froggy tissue, were producing electricity chemically. Volta managed to recreate this effect with discs of two different metals, silver and zinc, separated by pieces of cardboard soaked in saltwater, and that was how he came to invent the world's first proper battery —an invention that revolutionized the history of electricity. It was a perfect example of how a scientific discovery can be rapidly turned into a practical technology—and one that allowed science to advance even further by making experiments easier. Even in Volta's time, the discovery was considered so impressive that the inventor was asked to demonstrate it before the great French emperor Napoleon I, who set up the Galvanism Prize in his honor. (His nephew, Napoleon III, set up a Volta Prize to reward great scientific discoveries some years later.)

Volta's invention also led to the development of a new branch of science called electrochemistry. One of its founding fathers, Sir Humphry Davy (1778–1829), used a kind of electrochemistry known as electrolysis (effectively, making a battery work in reverse) to discover a number of chemical elements, including sodium and potassium, and later barium, calcium, magnesium, and strontium. Fittingly, he was awarded a Galvanism Prize for his work in 1807.

Magnetic attractions

There's electricity—and there's magnetism. That's how people like William Gilbert saw the world and it's still how we study it in schools to this day. The idea is not wrong, but it's a little bit misleading, because electricity and magnetism are essentially two different ways of looking at the same, bigger phenomenon. They're like two sides of the same coin or the front and back of a house. There had been various clues about the links between electricity and magnetism over the years. (In 1735, for example, the scientific journal Philosophical Transactions of the Royal Society of London had carried "An account of an extraordinary effect of lightning in communicating magnetism" : according to a doctor in Yorkshire, a lightning bolt had struck the corner of a house where a large box of metal knives and forks were stored, scattering them around and, curiously, magnetizing them in the process.) But the definitive connection between electricity and magnetism was really first established by a series of revolutionary experiments that European scientists carried out in the 19th century.

The person who gets the credit for discovering what we now know as electromagnetism was Danishman Hans Christian Oersted (1777–1851), a physics professor in Copenhagen who had been inspired by Volta's invention of the battery. [6] Around 1820, during a student lecture, he just happened to place a compass near an electric wire and switched on the current. Incredibly, he noticed that the sudden current made the compass needle move, while reversing the current made the needle move the opposite way, suggesting the electricity flowing through the wire was making magnetism (because that's what a compass detects). [7] Though this was a major discovery, it wasn't the first proof of electromagnetism. About 20 years earlier, an Italian philosopher named Gian Domenico Romagnosi (1761–1835) had done a similar experiment, but few remember him today. [8]

Animation: Oersted's experiment: When he placed a compass near a wire and switched on the current, the compass needle moved one way; when he reversed the current in the wire, the needle moved the opposite way.

“ ...the magnetical effects are produced by the same powers as the electrical... all phenomena are produced by the same original power ” Hans Christian Oersted [9]

After learning of Oersted's work, Frenchman Andre-Marie Ampère (1775–1836) carried out another groundbreaking experiment with two wires placed side by side. When he switched on the current, he found the wires could push apart or pull together. One of his important conclusions was that a current-carrying wire makes a magnetic field at right angles, in concentric circles around the wire—rather like the ripples on a pond when you drop a stone into it.

This was all very interesting, but what use could it possibly be? Step forward English chemist and physicist Michael Faraday (1791–1867), originally an assistant to Sir Humphry Davy, who took "Ampère's beautiful theory" (as he called it) a stage further. [10] Ingeniously, he found he could make a wire rotate by passing electricity through it, because the flowing current created a magnetic field around it that would push against the field of a nearby magnet—and so invented a very primitive and not very practical electric motor . A few years later, he realized this invention would also work in reverse: if he moved a wire through a magnetic field, he could make electricity surge through it. That marked the invention of the electricity generator —a simple but revolutionary device that now provides virtually all the electricity we use to this day. Faraday, though he stood on the shoulders of Oersted, Ampère, and those who came before, arguably made the greatest contribution to our modern age of electric power.

Photo: Joseph Henry, America's answer to Michael Faraday, is honored by this statue at the US Library of Congress Thomas Jefferson Building. Photo by Carol M. Highsmith. Credit: Library of Congress Series in the Carol M. Highsmith Archive, courtesy of Library of Congress , Prints and Photographs Division.

Faraday wasn't the only pioneer of electromagnetism, however. Elsewhere in the UK, William Sturgeon (1783–1850), a brilliant but undeservedly forgotten inventor, was carrying out very similar experiments. In 1825, between Faraday's inventions of the electric motor and generator, Sturgeon built the first powerful electromagnet by coiling wire around an iron bar and sending a current through it. Over in the United States, in 1831, physicist Joseph Henry (1797–1879) made far bigger and better electromagnets (reputedly boosting the strength of the magnetic field by using wire insulated with cloth torn from his wife's undergarments) until he'd built a huge electromagnet that could lift a ton in weight. [11] Powerful electromagnets like this are still used in junkyards to this day to heave metal car bodies from one place to another. The following year, Sturgeon built the first practical, modern electric motor , using an ingenious device called a commutator that keeps the motor's axle rotating in the same direction.

A powerful force

Motors and generators—two parts of Faraday's very impressive legacy—are the twin bedrocks of our modern electric world. Generators make electric power, motors take that power and do useful things, from pushing electric cars down the road to sucking up dirt in your vacuum. But electrical energy doesn't come from thin air; as Volta showed, it doesn't even come magically from dead animals. If we want a certain amount of electrical energy, we have to produce it from at least as much of another kind of energy. That's a basic law of physics known as the law of conservation of energy , largely figured out by Scottish physicist James Prescott Joule (1818–1889) in the 1830s. Joule showed how different kinds of energy—including ordinary movement (mechanical energy), heat , and electricity—could be converted into one another. [13] What Joule's work means, essentially, is that if you want to run a huge city like New York or Sao Paulo off electricity, you'll need to harness huge amounts of some other kind of energy to do it. So, for example, you'll need a giant power station burning huge amounts of coal, hundreds of wind turbines, or a vast area of solar cells .

Photo: Power pioneer: Thomas Edison built the first practical power plants, which made electricity from coal using dynamos like this evolved by Michael Faraday's generator. Photo by H.C. White Co., courtesy of US Library of Congress .

Making enough energy to supply towns and cities with electricity became possible when a Belgian engineer named Zénobe Gramme (1826–1901) built the first large-scale, practical direct-current (DC) generators in the 1870s. In 1881, the world's first power plant opened in the small town of Godalming, England. The following year, Thomas Edison (1846–1931) built the first full-scale power plant at 257 Pearl Street in Manhattan, New York City. While Edison opted for plants that produced DC electricity, his former employee turned bitter rival Nikola Tesla (1856–1943) thought alternating current would work much better, since, among other things, it could be used to transmit power efficiently over very long distances. Tesla teamed up with engineer George Westinghouse (1846–1914), and the two launched a bitter battle with Edison—now known as the War of the Currents —until they'd firmly established AC as the victor. Today, though AC remains the heart of the electricity "grid" systems that provide much of the world's power, DC has again grown in importance thanks, in particular, to things like solar cells, which generate direct (rather than alternating) current. [14]

Waving hello

Photo: James Clerk Maxwell. Public domain photo by courtesy of Wikimedia Commons .

By the end of the 19th century, electricity and magnetism were happily married in motors and generators, but what was the real connection between them? Why did one produce the other? The mystery was largely solved in the second half of the 19th century by a brilliant Scottish physicist named James Clerk Maxwell (1831–1879). In 1873, building on Michael Faraday's work, Maxwell published a complete theory of electromagnetism, neatly summarizing everything that was then known about electricity and magnetism in four apparently simple mathematical equations . Maxwell's theory explained how static or moving electric charges create electric fields around them, while magnetic poles (the ends of magnets) make magnetic fields. It also showed how electric fields can create magnetism and magnetic fields can make electricity, and tied electromagnetism together with light. This was one of the most fundamental and far-reaching theories of physics advanced so far—as radically important as Newton's work on gravity . Of course, electricity and magnetism were just the same as they had always been. What was different, following the work of James Clerk Maxwell, was a bold new understanding of how they worked together: a revolutionary new piece of science. And as the 19th century rolled on, technology advanced too: with the work of Edison, Tesla, and others, there was a growing understanding of how electromagnetism could put to good use as a practical way of storing and transmitting energy. All that was remarkable enough, but thanks to Maxwell's insights, linking electricity and magnetism to light waves, electromagnetism would soon change the world in another very important way: as a form of communication.

Photo: Champion of radio: Guglielmo Marconi didn't discover the basic science behind radio, but his amazing demonstrations of its usefulness transformed it into a winning technology. Color lithograph charicature of Marconi by Sir L. Ward (Spy), 1905. courtesy of the Wellcome Collection published under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence.

The first inkling of an exciting new form of electromagnetism came the decade after Maxwell had died. Maxwell had realized that electromagnetism could travel in waves. In 1888, a German physicist named Heinrich Hertz (1857–1894) found he could make some of these waves, in which electrical and magnetic energy tangoed through the air at the speed of light. [15] Apart from confirming Maxwell's ideas, this scientific advance opened up another new bit of technology: a practical way for sending information wirelessly from one place to another. English physicist Sir Oliver Lodge (1851–1940), who had been carrying out similar research to Hertz, and Italian Guglielmo Marconi (1874–1937), a brilliant showman with a gift for popularizing science, were among those who developed this technology. Originally called "ether waves," and now much better known to us as radio , it evolved into radar , television , satellite communication, remote control , Wi-Fi , and a whole variety of other things.

The source of electricity

Electricity has always been magical. Imagine how enthralled Thales must have been when he first saw static over 2500 years ago. Or what Heinrich Hertz felt like as he made the first radio waves in his laboratory in Karlsruhe in 1888. At the dawn of the 20th century, electricity seemed magical in all sorts of ways. Thomas Edison was building bold power plants and switching the world to the wonders of incandescent electric light . Marconi, meanwhile, was bouncing radio waves around the world. And there was a new kind of electrical magic as well: the dawning realization that electricity and magnetism originated from tiny particles inside atoms.

The idea that there must be a kind of "particle of electricity" had originally been put forward in 1874 by Irishman George Johnstone Stoney (1826–1911), who had previously studied the kinetic theory (how gas particles carried heat ). [16] Similar ideas were advanced in 1881 by German physicist Hermann von Helmholtz (1821–1894) and Dutchman named Hendrik Antoon Lorentz (1853–1928); together, these three developed the modern "particle" theory of electricity, in which static charges are seen as a build up of electric particles, while electric currents involve a flow of these particles from place to place. But what were the particles? The growing understanding of atoms and the world inside them, by Ernest Rutherford (1871–1937) and his colleagues, offered up a possible candidate in the shape of the electron, a particle Stoney named in 1891. Electrons were finally discovered in 1897 by British physicist J.J. Thomson (1856–1940), while he was playing around with a gadget called a cathode-ray tube, rather like an old-fashioned TV set. [17]

Animation: Solid-state physics explains that electric current is carried by electrons (blue) moving through materials.

During the 20th century, scientists came to understand not just how electrons power electricity and magnetism, but how they're involved in all kinds of other physical phenomena, including heat and light . Known as solid-state physics, these scientific ideas have led to some revolutionary electronic technologies, including the transistor , integrated circuits for computers, solar cells , and superconductors (materials with little or no electrical resistance).

Today, as the world grapples with pressing problems like air pollution and climate change , the need to switch from dirty fuels to cleaner forms of power has made electricity more important to us than ever. Back in Thales' time, electricity was just a take-it-or-leave-it, magical curiosity; today, it's central to our world and everything we do. The story of electricity runs, like a current, right through our past. Thanks to the brilliant work of these scientists and inventors, it also points to a bright and hopeful future.

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Find out more, on this website.

• Static electricity

For younger readers

• The Attractive Story of Magnetism with Max Axiom, Super Scientist by Andrea Gianopoulos. Capstone Press, 2008/2019. A graphic book with a companion app.
• Scientific Pathways: Electricity by Chris Woodford. Rosen, 2013: My quick introduction to electrical history. Previously published by Blackbirch in 2004 under the series title Routes of Science.
• Charged Up: The Story of Electricity by Jackie Bailey and Matthew Lilly. Picture Window Books/A & C Black, 2004. A graphic-style history that will appeal to reluctant readers.
• DK Biographies: Thomas Edison by Jan Adkins. DK, 2009. A well-illustrated, curriculum linked, short biography for younger readers aged 9–12.

For older readers

• The Age of Edison: Electric Light and the Invention of Modern America by Ernest Freeberg. Penguin, 2013.
• The Wizard of Menlo Park: How Thomas Alva Edison Invented the Modern World by Randall E. Stross. Crown Publishing Group, 2008.

Scholarly articles

• Bibliographical History Of Electricity And Magnetism by Paul Fleury Mottelay. Charles Griffin, 1922.
• Origin of the Electrical Fluid Theories by Fernando Sanford, The Scientific Monthly, Vol 13, No 5, Nov 1921, pp.448–459.

Primary sources

• Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein by Morris H. Shamos. Dover, 1959/1987. A wonderful collection of original papers, including groundbreaking electromagnetic experiments by Hans Christian Oersted, Michael Faraday, James Joule, J.J. Thomson, and Robert Millikan.
• Experiments and Observations on Electricity by Benjamin Franklin, The American Journal of Science and Arts, 1769.
• On the Production of Currents and Sparks of Electricity from Magnetism by Joseph Henry, The American Journal of Science and Arts, 1832.
• ↑     Origin of the Electrical Fluid Theories by Fernando Sanford, The Scientific Monthly, Vol 13, No 5, Nov 1921, pp.448–459.
• ↑     Speculation and Experiment in the Background of Oersted's Discovery of Electromagnetism by Robert C. Stauffer, Isis, Vol 48 No 1, March 1957, pp.33–50.
• ↑    "Chapter 9: Hans Christian Oersted: Electromagnetism" in Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein by Morris H. Shamos. Dover, 1959/1987, p.121.
• ↑     Speculation and Experiment in the Background of Oersted's Discovery of Electromagnetism by Robert C. Stauffer, Isis, Vol 48 No 1, March 1957, p.33.
• ↑    "Beautiful theory": "Chapter 10: Michael Faraday: Electromagnetic Induction and Laws of Electrolysis" in Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein by Morris H. Shamos. Dover, 1959/1987, p.131.
• ↑     Henry discusses this in On the Production of Currents and Sparks of Electricity from Magnetism by Joseph Henry, The American Journal of Science and Arts, 1832.
• ↑    Franklin describes the kite experiment in "Letter XI," Experiments and Observations on Electricity by Benjamin Franklin, The American Journal of Science and Arts, 1769, p.111.
• ↑    "Chapter 12: James Joule: The Mechanical Equivalent of Heat" in Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein by Morris H. Shamos. Dover, 1959/1987, p.166.
• ↑    Some reasons for DC's resurgence are set out in Edison's Final Revenge: The system of DC power generation and local distribution that the great inventor championed is set for a comeback by David Schneider, American Scientist, Vol 96 No 2, March–April 2008, pp.107–108.
• ↑    "Chapter 13: Heinrich Hertz: Electromagnetic waves" in Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein by Morris H. Shamos. Dover, 1959/1987, p.184.
• ↑    " George Johnstone Stoney, F.R.S., and the Concept of the Electron by J. G. O'Hara, Notes and Records of the Royal Society of London, Vol 29, No 2, March 1975, pp.265–276.
• ↑    "Chapter 16: J.J. Thomson: The Electron" in Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein by Morris H. Shamos. Dover, 1959/1987, p.216.

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History of Electricity

Affordable, reliable electricity is fundamental to modern life. Electricity provides clean, safe light around the clock, it cools our homes on hot summer days (and heats many of them in winter), and it quietly breathes life into the digital world we tap into with our smartphones and computers. Although hundreds of millions of Americans plug into the electric grid every day, most of us don’t give the history of electricity a second thought. Where does it come from? What’s its story?

When we take a fresh look at electricity, we see that keeping America powered up is actually an amazing feat—an everyday miracle. Here’s the Story of Electricity.

Revolutionary Power

Although people have known about electricity since ancient times, they’ve only been harnessing its power for about 250 years. Benjamin Franklin’s electricity experiments – including his famous kite experiment in 1752 – showed just how little we knew about electricity in the era of the American revolution and the first industrial revolution.[1] In the time since Franklin’s experiments, our grasp of electricity has grown tremendously, and we are constantly finding new ways to use it to improve our lives.

Ben Franklin’s famous kite experiment

One of the first major breakthroughs in electricity occurred in 1831, when British scientist Michael Faraday discovered the basic principles of electricity generation.[2] Building on the experiments of Franklin and others, he observed that he could create or “induce” electric current by moving magnets inside coils of copper wire. The discovery of electromagnetic induction revolutionized how we use energy. In fact, Faraday’s process is used in modern power production, although today’s power plants produce much stronger currents on a much larger scale than Faraday’s hand-held device.

In the era of modern power plants, coal has always generated more electricity in the U.S. than any other fuel source. In recent decades, we have seen other sources compete for second place: first hydroelectricity, then natural gas, nuclear power, and natural gas again.

Electricity generation mix by fuel type, 1949-2011

We also use electricity to power an increasing number of devices. Our modern electric world began with applications like the telegraph, light bulb, and telephone, and continued with radio, television, and many household appliances. Most recently, electrons have powered the digital age to create what energy expert Vaclav Smil calls our “instantaneously interconnected global civilization.”[3] Technology expert Mark Mills points out that electricity powers an increasing portion of our economy. The always-on data centers that support the internet and “cloud computing” will continue to increase demand for electricity, overwhelming the modest decreases in electricity use in other parts of the economy, such as manufacturing processes.[4][5]

The ever-growing applications of electricity explain the increasing use of fuels like natural gas, oil, and coal in power generation as opposed to direct uses such as heating or transportation. In 1900, for example, less than two percent of natural gas, oil, and coal were used to make electricity. A century later, 30 percent of our use of natural gas, oil, and coal was devoted to electric power.[6] Smil explains electricity’s appeal: “Electricity is the preferred form of energy because of its high efficiency, instant and effortless access, perfect and easily adjustable flow, cleanliness, and silence at the point of use.”[7]

Increased electricity access has lit corners of the world that were once dark. As international development groups and economists point out, access to electricity is a hallmark of advanced societies and a basic requirement for economic progress.[8] “Next to the increasing importance of hydrocarbons as sources of energy,” economist Erich Zimmermann wrote in 1951, “the rise of electricity is the most characteristic feature of the so-called second industrial revolution.”[9] In recent years, people in countries from China to Kenya have experienced rising living standards, as more people are able to use electricity to keep their homes and schools cool during torrid summers, to refrigerate food that would have otherwise spoiled, and to purify water that would have otherwise been unsafe to drink.

There is, of course, still much more to be done. In 2009, the International Energy Agency estimated that nearly 70 percent of people in Sub-Saharan Africa lacked access to electricity. That means 585.2 million people remain in the dark.[10]

Many parts of the world remain in the dark. 

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The Dawn of Electric Light in the U.S.

One of the greatest pioneers in electricity was Thomas Edison, who saw electricity as his “field of fields” to “reorganize the life of the world.” Working tirelessly on electricity from his laboratory in New Jersey in the 1870s, America’s greatest inventor brought the incandescent electric light bulb into practical use by the end of that decade and patented the incandescent light bulb in 1880.[11] “When Edison…snatched up the spark of Prometheus in his little pear-shaped glass bulb, ”German historian Emil Ludwig observed, “it meant that fire had been discovered for the second time, that mankind had been delivered again from the curse of night.”[12] Yet Edison’s electric light was even better than fire—it was brighter, more consistent, and safer than the flame of candles or lamps.

Edison’s light bulb was one of the first applications of electricity to modern life. He initially worked with J. P. Morgan and a few privileged customers in New York City in the 1880s to light their homes, pairing his new incandescent bulbs with small generators. Edison’s electric lighting systems were basic by today’s standards but bold at the time—they not only threatened the existing gas lighting industry but radically challenged the status quo by introducing people to an entirely new type of energy. In a few short years, Edison transformed electricity from a science experiment into an exciting, safe, and coveted luxury.

The light bulb—a symbol of innovation and the invention that sparked the electricity revolution.

The Rise of an Industry

In order for the magic of electricity to truly take hold in American life, new industries were needed to build the generators to supply electric power, as well as the new appliances and electric lights that used it. In 1882, with J.P. Morgan funding his efforts, Edison launched the businesses that would later be known as General Electric. In September of that year, he opened the United States’ first central power plant in lower Manhattan—the Pearl Street Station.

Pearl Street was a stroke of genius. Edison connected a large bank of generators to homes and businesses (including the New York Times) in the immediate area through a network of buried copper wires. At that time, there was no “electric grid.” Before Pearl Street, customers who wanted power for electric lights or motors relied on generators located on-site, typically in the basement. Pearl Street’s “central” power plant design was an important shift from small-scale, on-site generation to industrial-scale power, and soon became the model for the entire power generation industry.[13]

The Dynamo Room at the Pearl Street Station, the first power plant in the U.S. 

Enter Samuel Insull

Although Edison was a brilliant inventor, he was a disorganized businessman. His inventions came to him faster than the financial capital necessary to carry them out, and Edison preferred to focus on the inventions themselves rather than the paperwork they created. The inventor needed a managerial counterpart. That counterpart arrived in 1881, in the form of a promising 21-year-old from England. Samuel Insull, who began his career in the U.S. as a personal assistant to Edison, astounded the inventor with his business prowess—so much so that Edison soon granted Insull power of attorney over his businesses.[14] But the work with Edison would be just the beginning for Insull—over the next four decades, he built an electricity business that made him the Henry Ford of the modern electricity industry.

Electricity required a different business model because it was different than virtually every other commodity. Electricity had to be consumed the moment it was produced. (Storage was very costly and limited—and still is.) In order for electricity to become accessible and affordable, someone needed to bring together mass efficiencies in production and consumption. Insull saw the opportunities in front of him. Whoever mastered the engineering and the economics of the power grid could take the reins of the rising electricity industry—an industry that was already toppling the stocks of gas light companies and attracting big investors like J.P. Morgan. In 1892, Insull left his job as an executive at the lighting company Edison started (General Electric near New York City) for Chicago Edison (an electricity generation/distribution company, later known as Commonwealth Edison).[15] It was a move that would indelibly change the industry.

Early transmission lines in rural America. Photo Credit: Towers

Insull Builds the Modern Power Grid

Insull was able to achieve what economists call “economies of scale” (cost savings from large-scale operations) by consolidating the mom-and-pop electricity providers and closing small generators in favor of larger, more efficient units manufactured by General Electric. He also found efficiencies in customer sales—the more customers he had, the more efficiently he could run his generators, and the cheaper it was to provide power. As Insull’s business grew, he was able to find better ways of providing electricity to more and more people.

1903 turbine hall at Fisk Street Station 

Insull became a master salesman for all things electric. In order to use his generators more efficiently (i.e., run them at full capacity for more hours of the day), he offered to power elevators and streetcars during the daytime when there was less demand for electric lighting.

Insull also used high-voltage transmission lines to spread electricity to the suburbs and then to the countryside. Because customers inside and outside cities used power at different times, Insull was able to provide power to both types of customers more efficiently than if he had served them independently. Such diversification, served by ever-larger and more efficient generators, brought the price of a kilowatt-hour down. Electricity prices fell year after year as the young industry grew between 1902 to 1930.

To be able to provide power for “peaky” customers, Insull implemented a demand charge (a fixed fee) in addition to the typical usage charge. That way, the customer paid for the privilege to use a lot of electricity in a little time. In this way, Insull could profitably expand his business to include all types of customers.

Lastly, Insull found efficiencies by interconnecting or “networking” power grids for backup and reliability, eliminating the need to build (redundant) generation in the same service area.

Consolidation. Mass production. Mass consumption. Rural electrification. Two-part pricing. Networked power. Samuel Insull did for electricity what Henry Ford did for the automobile—he turned a luxury product into an affordable part of everyday life for millions of Americans. Where Edison provided the novelty of electric light to Manhattan’s upper class, Insull’s innovations made electricity accessible to all.

Electricity Becomes Politicized

The electricity industry in the U.S. was intertwined with politics from the beginning. Before Pearl Street ever opened, Edison had to bribe New York politicians just to begin laying the foundations of his work. As Time magazine recounts, Edison “obtained with great difficulty the consent of New York’s famously corrupt city government to build his proposed network on the southern tip of Manhattan. (He got their approval in part by plying them with a lavish champagne dinner at Menlo Park catered by Delmonico’s, then New York’s finest restaurant.)”[17] As the early electricity industry grew, it became more involved with city politics over lighting contracts. Electricity providers had to receive franchise rights from city officials in order to serve local areas, opening the door for those officials to extort power companies for campaign contributions or personal bribes.

Insull’s solution was new legislation that would replace local regulation with statewide regulation of power companies by public utility commissions (modeled after state railroad commissions). In this arrangement, the state commissions would establish a maximum rate for the power company to charge its customers based on the company’s cost of providing electric service (plus a reasonable rate of return).

In exchange for such rate regulation, the state commissions gave the power company an exclusive franchise to serve a given geographical area (a legal monopoly). The early electricity industry was a natural monopoly (according to many economists and regulators, and Insull himself) which turned out to be a self-fulfilling prophecy: state regulators assumed power companies were bound to be monopolies, so they regulated them accordingly and gave them legal monopoly status. The prospect of a true, laissez-faire electricity market was never on the table.

Insull needed time and a huge public relations effort to convince the industry that statewide public utility regulation was the best way to provide low-cost power and dodge harsh local regulation or takeover. Wisconsin and New York were the first states to extend state-level rate regulation to the electricity industry in 1907. By 1914, forty-three other states had followed suit and created state-level commissions to oversee electric utilities.[19]

These state public utility commissions, formed in the early 20 th century, still regulate utilities. In theory, their rate regulation is supposed to protect the consumer, but in practice it often benefits other interest groups—or the utilities themselves—at the expense of consumers. Despite these regulations, Insull continued to provide inexpensive power to a greater number of customers through the first three decades of the 20 th century.

Tragically, the Great Depression financially ruined Insull’s expanding enterprises. His indebted holding company collapsed and legal battles ensued. Facing trial in 1934, he was quoted in newspapers as saying “I am fighting not only for freedom but for complete vindication. I have erred, but my greatest error was in underestimating the effects of the financial panic on American securities, and particularly on the companies I was trying to build. I worked with all my energy to save those companies.”[20]

Insull was acquitted but lost his companies and wealth, and fell into disrepute and obscurity. Public knowledge of his contributions as a pioneer of the modern power grid seems to have died along with him in 1938. As Forrest McDonald wrote of the acquittal in Insull’s biography, “For his fifty-three years of labor to make electric power universally cheap and abundant, Insull had his reward from a grateful people: He was allowed to die outside prison.”[21]

State regulation and Insull’s tragic fall ultimately led to federal intervention into electricity beyond hydroelectric licensing, the founding job of the Federal Power Commission (est. 1920.) In 1935, the Federal Power Act authorized the Federal Power Commission—now the Federal Energy Regulatory Commission (FERC)—to apply “just and reasonable” cost-based rate regulation to the wholesale power market (along the same lines as state-level regulation of retail rates). Another law, the Public Utility Holding Company Act of 1935, required multi-state companies to divest properties to operate in only one state.[22]

Federal intervention grew again in the energy-troubled 1970s. The Public Utility Regulatory Policies Act of 1978 required electric utilities to buy power from independent generators, successfully creating a new industry segment but also opening the door for intermittent generation from renewable sources to enter—and even destabilize—the growing grid. 23] In fear of using up limited energy and natural resources, Congress also passed new legislation designed to curb electricity use and promote environmental goals. New agencies such as the Environmental Protection Agency (1970) and the Department of Energy (1977) were created to regulate different aspects of electricity, including generation from coal-burning power plants.

In the 1990s, federal regulation of electricity shifted towards a market-based approach.[24] Deregulation had proven beneficial in reducing the cost and improving the quality of tightly regulated areas like the airline industry, and regulators were interested in bringing the same benefits to the electricity industry.

In 1996, FERC attempted to restructure the industry by imposing an “open access” model[25] on utilities.[26] FERC’s intent was to “remove impediments to competition in the wholesale bulk power marketplace.” Despite FERC’s focus on competition, electricity transmission remains heavily regulated. Hence, the “deregulation” of electricity in the 1990s was in fact “re-regulation.” Wholesale electricity markets continue to evolve, with market forces and federal regulations colliding at each step.

Currently, the electric power sector faces an unprecedented amount of federal intervention from several different agencies. Some of the most active are the Environmental Protection Agency (EPA), FERC, and the Department of Energy.[27]

The EPA proposed a new rule in 2014 to limit carbon dioxide emissions from existing power plants. The rule threatens to close a large portion of the reliable coal-fired electricity supply in the U.S. As a result, the rule will undercut power companies’ ability to meet electricity demand safely and reliably.[28] The EPA rule also comes at huge cost to American families and businesses that use electricity every day—by 2030, the rule is estimated to increase electricity bills by a combined $290 billion.[29]

FERC, with its mandate to ensure just and reasonable wholesale rates, has long been involved in every aspect of wholesale electricity markets. In 2005, it received increased authority from Congress to further regulate the reliability of the power grid, and to oversee wholesale electricity markets. Recent FERC rules favoring renewable sources of electricity have made the agency more political than ever before and raised its profile. Conflicts over FERC leadership—between Congress, the White House, and policy and industry groups—reached a fever pitch in 2013 and 2014 with two nominees to chair the agency being denied the job by Congress.

Meanwhile, the Department of Energy has also encouraged renewable sources of electricity through its national laboratories and essentially banned the use of certain technologies—such as the familiar incandescent light bulb—by establishing energy efficiency mandates. In short, nearly every aspect of electricity is now heavily regulated by multiple federal agencies.

A Powerful Vision

Electricity remains a growth industry today, in spite of political meddling at the local, state, and federal level. New vistas for electricity will always be there for people to discover, but that discovery will require the freedom to inspire new inventions. Let the next generation of electricity entrepreneurs be driven—like Edison and Insull—by the productive forces of human ingenuity and healthy competition.

Electricity is modern life. Without access to reliable power, our lives would be much more like they were before the industrial revolution (to quote Thomas Hobbes): “solitary, poor, nasty, brutish, and short.”[30] Nearly every feature of modern civilization depends on affordable, reliable electricity and the things it powers—lamps and heaters to safely keep our homes well-lit and comfortable, smart phones to stay in touch with loved ones, and always-on data centers to give us a reliable Internet—among countless others. It is so crucial to modern life, in fact, that the history of electricity is really the history of the modern world.

Photo Credit: Wikipedia Commons

_____________________________________________________________________

[1] Carl Van Doren, An Account of the Kite Experiment , UShistory.org, http://www.ushistory.org/franklin/info/kite.htm

[2] engineering timelines, faraday’s work- the electrical generation, http://www.engineering-timelines.com/how/electricity/generator.asp, [3]vaclav smil, the energy question, again , current history, december 2000, p. 408., [4] mark p. mills, the cloud begins with coal, august 2013, http://www.tech-pundit.com/wp-content/uploads/2013/07/cloud_begins_with_coal.pdfc761ac, [5] energy information administration, manufacturing energy consumption data show large reductions in both manufacturing energy use and the energy intensity of manufacturing activity between 2002 and 2010 , march 19, 2013, http://www.eia.gov/consumption/manufacturing/reports/2010/decrease_use.cfm, [6]vaclav smil, “the energy question, again,” current history , december 2000, p. 409., [7]vaclav smil, “the energy question, again,” current history , december 2000, p. 409., [8] international energy agency, access to electricity, http://www.worldenergyoutlook.org/resources/energydevelopment/accesstoelectricity/, [9] erich zimmermann, world resources and industries (new york: harper & brothers, 1951), p. 596., [10] international energy agency, access to electricity, http://www.iea.org/publications/worldenergyoutlook/resources/energydevelopment/accesstoelectricity/, [11] national archives and records administration, thomas edison’s patent drawing for an improvement in electric lamps, patented january 27, http://www.archives.gov/exhibits/american_originals_iv/images/thomas_edison/patent_drawing.html, [12] these quotations are taken from robert bradley, edison to enron: energy markets and political strategies (hoboken, nj: scrivener publishing and john wiley & sons, 2011), p. 30., [13] robert l. bradley, edison to enron: energy markets and political strategies . (hoboken, nj: scrivener publishing and john wiley & sons, 2011), p. 42., [14] conot, robert. thomas a. edison: a streak of luck. new york: da capo, 1979. (p. 273), [15] comed, carrying on a history of innovation and service , https://www.comed.com/about-us/company-information/pages/history.aspx, [16] australian department of industry, energy efficiency exchange, http://eex.gov.au/energy-management/energy-procurement/procuring-and-managing-energy/understanding-your-energy-requirements/#why_are_demand_profiles_important, [17] thomas edison: his electrifying life, time magazine special edition, 2013., [18] r. richard geddes, a historical perspective on electric utility regulation, winter 1992 http://object.cato.org/sites/cato.org/files/serials/files/regulation/1992/1/v15n1-8.pdf, [19] emergence of electric utilities in america: state regulation , http://americanhistory.si.edu/powering/past/h1main.htm, [20] forrest mcdonald, insull (university of chicago, 1962)., [21] ibid., p. 333., [22] robert l. bradley, edison to enron: energy markets and political strategies . (hoboken, nj: scrivener publishing and john wiley & sons, 2011), p. 219, 513., [23] travis fisher, purpa: another subsidy for intermittent energies, january 22, 2013, http://www.masterresource.org/2013/01/purpa-renewable-energy-subsidies/, [24] market economics: the push for deregulation, http://americanhistory.si.edu/powering/past/h5main.htm, [25] clyde wayne crews, rethinking electricity deregulation: does open access have it wired- or tangled, june 24, 1999, http://cei.org/outreach-regulatory-comments-and-testimony/rethinking-electricity-deregulation-does-open-access-have, [26] federal energy regulatory commission, history of ferc, http://www.ferc.gov/students/ferc/history.asp, [27] institute for energy research, epa’s power plant carbon dioxide reduction mandate, https://www.instituteforenergyresearch.org/studies/111d-emissions-map, [28] institute for 21 st century energy, assessing the impact of proposed new carbon regulations in the united states, http://www.energyxxi.org/epa-regs#, [29] institute for 21 st century energy, assessing the impact of proposed new carbon regulations in the united states, http://www.energyxxi.org/sites/default/files/file-tool/assessing_the_impact_of_potential_new_carbon_regulations_in_the_united_states.pdf, [30] thomas hobbes, of man, being the first part of leviathan. chapter xiii of the natural condition of mankind as concerning their felicity and misery , the harvard classics 1909-14, http://www.bartleby.com/34/5/13.html.

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Electricity History

• Electricity Explained Channels

A Timeline Of History Of Electricity

By R.W. Hurst, Editor

Electricity development and history are very interesting. However, humankind's knowledge of magnetism and static electricity began more than 2,000 years before they were first recognized to be separate (though interrelated) phenomena. Once that intellectual threshold was crossed - in 1551 - scientists took more bold steps forward (and more than a few steps back) toward better understanding and harnessing these forces. The next 400 years would see a succession of discoveries that advanced our knowledge of magnetism, electricity and the interplay between them, leading to ever more powerful insights and revolutionary inventions.

This Timeline Of History Of Electricity highlights important events and developments in these fields from prehistory to the beginning of the 21st century.

600 BC  -  Thales of Miletus writes about amber becoming charged by rubbing - he was describing what we now call static electricity.

900 BC  -  Magnus, a Greek shepherd, walks across a field of black stones which pull the iron nails out of his sandals and the iron tip from his shepherd's staff (authenticity not guaranteed). This region becomes known as Magnesia.

600 BC  -  Thales of Miletos rubs amber ( elektron  in Greek) with cat fur and picks up bits of feathers.

1269  -  Petrus Peregrinus of Picardy, Italy, discovers that natural spherical magnets (lodestones) align needles with lines of longitude pointing between two pole positions on the stone.

1600  -  William Gilbert, court physician to Queen Elizabeth, first coined the term "electricity" from the Greek word for amber. Gilbert wrote about the electrification of many substances in his "De magnete, magneticisique corporibus". He also first used the terms electric force, magnetic pole, and electric attraction. He also discusses static electricity and invents an electric fluid which is liberated by rubbing.

ca. 1620  -  Niccolo Cabeo discovers that electricity can be repulsive as well as attractive.

1630  -  Vincenzo Cascariolo, a Bolognese shoemaker, discovers fluorescence.

1638 - Rene Descartes theorizes that light is a pressure wave through the second of his three types of matter of which the universe is made. He invents properties of this fluid that make it possible to calculate the reflection and refraction of light. The ``modern'' notion of the aether is born.

1638  -  Galileo attempts to measure the speed of light by a lantern relay between distant hilltops. He gets a very large answer.

1644  -  Rene Descartes theorizes that the magnetic poles are on the central axis of a spinning vortex of one of his fluids. This vortex theory remains popular for a long time, enabling Leonhard Euler and two of the Bernoullis to share a prize of the French Academy as late as 1743.

1657  -  Pierre de Fermat shows that the principle of least time is capable of explaining refraction and reflection of light. Fighting with the Cartesians begins. (This principle for reflected light had been anticipated anciently by Hero of Alexandria.)

1660  -  Otto von Guericke invented a machine that produced static electricity.

1665  -  Francesco Maria Grimaldi, in a posthumous report, discovers and gives the name of diffraction to the bending of light around opaque bodies.

1667  -  Robert Hooke reports in his  Micrographia  the discovery of the rings of light formed by a layer of air between two glass plates. These were actually first observed by Robert Boyle, which explains why they are now called Newton's rings. In the same work he gives the matching-wave-front derivation of reflection and refraction that is still found in most introductory physics texts. These waves travel through the aether. He also develops a theory of color in which white light is a simple disturbance and colors are complex distortions of the basic simple white form.

1671  -  Isaac Newton destroys Hooke's theory of color by experimenting with prisms to show that white light is a mixture of all the colors and that once a pure color is obtained it can never be changed into another color. Newton argues against light being a vibration of the ether, preferring that it be something else that is capable of traveling through the aether. He doesn't insist that this something else consist of particles, but allows that it may be some other kind of emanation or impulse. In Newton's own words, ``...let every man here take his fancy.''

1675  -  Olaf Roemer repeats Galileo's experiment using the moons of Jupiter as the distant hilltop. He measures m/s.

1678  -  Christiaan Huygens introduces his famous construction and principle, thinks about translating his manuscript into Latin, then publishes it in the original French in 1690. He uses his theory to discuss the double refraction of Iceland Spar. His is a theory of pulses, however, not of periodic waves.

1717  -  Newton shows that the ``two-ness'' of double refraction clearly rules out light being aether waves. (All aether wave theories were sound-like, so Newton was right; longitudinal waves can't be polarized.)

1728  -  James Bradley shows that the orbital motion of the earth changes the apparent motions of the stars in a way that is consistent with light having a finite speed of travel.

1729  -  Stephen Gray shows that electricity doesn't have to be made in place by rubbing but can also be transferred from place to place with conducting wires. He also shows that the charge on electrified objects resides on their surfaces.

1733  -  Charles Francois du Fay discovers that electricity comes in two kinds which he called  resinous (-) and  vitreous (+).

1742  -  Thomas Le Seur and Francis Jacquier, in a note to the edition of Newton's  Principia  that they publish, show that the force law between two magnets is inverse cube.

1745  -  Georg Von Kleist discovered that electricity was controllable. Dutch physicist, Pieter van Musschenbroek invented the "Leyden Jar" the first electrical capacitor. Leyden jars store static electricity.

1745  -  Pieter van Musschenbroek invents the Leyden jar, or capacitor, and nearly kills his friend Cunaeus.

1747  -  Benjamin Franklin invents the theory of one-fluid electricity in which one of Nollet's fluids exists and the other is just the absence of the first. He proposes the principle of conservation of charge and calls the fluid that exists and flows ``positive''. This educated guess ensures that undergraduates will always be confused about the direction of current flow. He also discovers that electricity can act at a distance in situations where fluid flow makes no sense.

1748  -  Sir William Watson uses an electrostatic machine and a vacuum pump to make the first glow discharge. His glass vessel is three feet long and three inches in diameter: the first fluorescent light bulb.

1749  -  Abbe Jean-Antoine Nollet invents the two-fluid theory electricity.

1750  -  John Michell discovers that the two poles of a magnet are equal in strength and that the force law for individual poles is inverse square.

1752  -  Johann Sulzer puts lead and silver together in his mouth, performing the first recorded ``tongue test'' of a battery.

1759  -  Francis Ulrich Theodore Aepinus shows that electrical effects are a combination of fluid flow confined to matter and action at a distance. He also discovers charging by induction.

1762  -  Canton reports that a red hot poker placed close to a small electrified body destroys its electrification.

1764  -  Joseph Louis Lagrange discovers the divergence theorem in connection with the study of gravitation. It later becomes known as Gauss's law. (See 1813).

1766  -  Joseph Priestly, acting on a suggestion in a letter from Benjamin Franklin, shows that hollow charged vessels contain no charge on the inside and based on his knowledge that hollow shells of mass have no gravity inside correctly deduces that the electric force law is inverse square.

ca 1775  -  Henry Cavendish invents the idea of capacitance and resistance (the latter without any way of measuring current other than the level of personal discomfort). But being indifferent to fame he is content to wait for his work to be published by Lord Kelvin in 1879.

1777  -  Joseph Louis Lagrange invents the concept of the scalar potential for gravitational fields.

1780  -  Luigi Galvani causes dead frog legs to twitch with static electricity, then also discovers that the same twitching can be caused by contact with dissimilar metals. His followers invent another invisible fluid, that of ``animal electricity'', to describe this effect.

1782  -  Pierre Simon Laplace shows that Lagrange's potential satisfies.

1785  -  Charles Augustin Coulomb uses a torsion balance to verify that the electric force law is inverse square. He also proposes a combined fluid/action-at-a-distance theory like that of Aepinus but with two conducting fluids instead of one. Fighting breaks out between single and double fluid partisans. He also discovers that the electric force near a conductor is proportional to its surface charge density and makes contributions to the two-fluid theory of magnetism.

1786  -  Italian physician, Luigi Galvani demonstrated what we now understand to be the electrical basis of nerve impulses when he made frog muscles twitch by jolting them with a spark from an electrostatic machine.

1793  -  Alessandro Volta makes the first batteries and argues that animal electricity is just ordinary electricity flowing through the frog legs under the impetus of the force produced by the contact of dissimilar metals. He discovers the importance of ``completing the circuit.'' In 1800 he discovers the Voltaic pile (dissimilar metals separated by wet cardboard) which greatly increases the magnitude of the effect.

1800  -  William Nicholson and Anthony Carlisle discover that water may be separated into hydrogen and oxygen by the action of Volta's pile.

1801  -  Thomas Young gives a theory of Newton's rings based on constructive and destructive interference of waves. He explains the dark spot in the middle by proposing that there is a phase shift on reflection between a less dense and more dense medium, then uses essence of sassafras (whose index of refraction is intermediate between those of crown and flint glass) to get a light spot at the center.

1803  -  Thomas Young explains the fringes at the edges of shadows by means of the wave theory of light. The wave theory begins its ascendance, but has one important difficulty: light is thought of as a longitudinal wave, which makes it difficult to explain double refraction effects in certain crystals.

1807  -  Humphrey Davy shows that the essential element of Volta's pile is chemical action since pure water gives no effect. He argues that chemical effects are electrical in nature.

1808  -  Laplace gives an explanation of double refraction using the particle theory, which Young attacks as improbable.

1808  -  Etienne Louis Malus, a military engineer, enters a prize competition sponsored by the French Academy ``To furnish a mathematical theory of double refraction, and to confirm it by experiment.'' He discovers that light reflected at certain angles from transparent substances as well as the separate rays from a double-refracting crystal have the same property of  polarization . In 1810 he receives the prize and emboldens the proponents of the particle theory of light because no one sees how a wave theory can make waves of different polarizations.

1811  -  Arago shows that some crystals alter the polarization of light passing through them.

1812  -  Biot shows that Arago's crystals rotate the plane of polarization about the propagation direction.

1812  -  Simeon Denis Poisson further develops the two-fluid theory of electricity, showing that the charge on conductors must reside on their surfaces and be so distributed that the electric force within the conductor vanishes. This surface charge density calculation is carried out in detail for ellipsoids. He also shows that the potential within a distribution of electricity satisfies the equation.

1812  -  Michael Faraday, a bookbinders apprentice, writes to Sir Humphrey Davy asking for a job as a scientific assistant. Davy interviews Faraday and finds that he has educated himself by reading the books he was supposed to be binding. He gets the job.

ca. 1813  -  Laplace shows that at the surface of a conductor the electric force is perpendicular to the surface.

1813  -  Karl Friedrich Gauss rediscovers the divergence theorem of Lagrange. It will later become known as Gauss's law.

1815  -  David Brewster establishes his law of complete polarization upon reflection at a special angle now known as Brewster's angle. He also discovers that in addition of uniaxial cystals there are also biaxial ones. For uniaxial crystals there is the faint possibility of a wave theory of longitudinal-type, but this appears to be impossible for biaxial ones.

1816  -  David Brewster invents the kaleidoscope. First energy utility in US founded.

1816  -  Francois Arago, an associate of Augustin Fresnel, visits Thomas Young and describes to him a series of experiments performed by Fresnel and himself which shows that light of differing polarizations cannot interfere. Reflecting later on this curious effect Young sees that it can be explained if light is transverse instead of longitudinal. This idea is communicated to Fresnel in 1818 and he immediately sees how it clears up many of the remaining difficulties of the wave theory. Six years later the particle theory is dead.

1817  -  Augustin Fresnel annoys the French Academy. The Academy, hoping to destroy the wave theory once and for all, proposes  diffraction  as the prize subject for 1818. To the chagrin of the particle-theory partisans in the Academy the winning memoir in 1818 is that of Augustin Fresnel who explains diffraction as the mutual interference of the secondary waves emitted by the unblocked portions of the incident wave, in the style of Huygens. One of the judges from the particle camp of the Academy is Poisson, who points out that if Fresnel's theory were to be indeed correct, then there should be a bright spot at the center of the shadow of a circular disc. This, he suggests to Fresnel, must be tested experimentally. The experiment doesn't go as Poisson hopes, however, and the spot becomes known as ``Poisson's spot.''

1820  -  Hans Christian Oersted discovers that electric current in a wire causes a compass needle to orient itself perpendicular to the wire.

1820  -  Andre Marie Ampere, one week after hearing of Oersted's discovery, shows that parallel currents attract each other and that opposite currents attract.

1820  -  Jean-Baptiste Biot and Felix Savart show that the magnetic force exerted on a magnetic pole by a wire falls off like 1/ r  and is oriented perpendicular to the wire. Whittaker then says that ``This result was soon further analyzed,'' to obtain

1820  -  John Herschel shows that quartz samples that rotate the plane of polarization of light in opposite directions have different crystalline forms. This difference is helical in nature.

1821  -  Faraday begins electrical work by repeating Oersted's experiments. First electric motor (Faraday).

1821  -  Humphrey Davy shows that direct current is carried throughout the volume of a conductor and establishes that for long wires. He also discovers that resistance is increased as the temperature rises.

1822  -  Thomas Johann Seebeck discovers the thermoelectric effect by showing that a current will flow in a circuit made of dissimilar metals if there is a temperature difference between the metals.

1824  -  Poisson invents the concept of the magnetic scalar potential and of surface and volume pole densities described by the formulas. He also finds the magnetic field inside a spherical cavity within magnetized material.

1825  -  Ampere publishes his collected results on magnetism. His expression for the magnetic field produced by a small segment of current is different from that which follows naturally from the Biot-Savart law by an additive term which integrates to zero around closed circuit. It is unfortunate that electrodynamics and relativity decide in favor of Biot and Savart rather than for the much more sophisticated Ampere, whose memoir contains both mathematical analysis and experimentation, artfully blended together. In this memoir are given some special instances of the result we now call Stokes theorem or as we usually write it. Maxwell describes this work as ``one of the most brilliant achievements in science. The whole, theory and experiment, seems as if it had leaped, full-grown and full-armed, from the brain of the `Newton of electricity'. It is perfect in form and unassailable in accuracy; and it is summed up in a formula from which all the phenomena may be deduced, and which must always remain the cardinal formula of electrodynamics.''

1825  -  Fresnel shows that combinations of waves of opposite circular polarization traveling at different speeds can account for the rotation of the plane of polarization.

1826  -  Georg Simon Ohm establishes the result now known as Ohm's law.  V = IR  seems a pretty simple law to name after someone, but the importance of Ohm's work does not lie in this simple proportionality. What Ohm did was develop the idea of voltage as the driver of electric current. He reasoned by making an analogy between Fourier's theory of heat flow and electricity. In his scheme temperature and voltage correspond as do heat flow and electrical current. It was not until some years later that Ohm's electroscopic force ( V  in his law) and Poisson's electrostatic potential were shown to be identical.

1827  -  Augustin Fresnel publishes a decade of research in the wave theory of light. Included in these collected papers are explanations of diffraction effects, polarization effects, double refraction, and Fresnel's sine and tangent laws for reflection at the interface between two transparent media.

1827  -  Claude Louis Marie Henri Navier publishes the correct equations for vibratory motions in one type of elastic solid. This begins the quest for a detailed mathematical theory of the aether based on the equations of continuum mechanics.

1827  -  F. Savery, after noticing that the current from a Leyden jar magnetizes needles in alternating layers, conjectures that the electric motion during the discharge consists of a series of oscillations.

1828  -  George Green generalizes and extends the work of Lagrange, Laplace, and Poisson and attaches the name  potential  to their scalar function. Green's theorems are given, as well as the divergence theorem (Gauss's law), but Green doesn't know of the work of Lagrange and Gauss and only references Priestly's deduction of the inverse square law from Franklin's experimental work on the charging of hollow vessels.

1828  -  Augustine Louis Cauchy presents a theory similar to Navier's, but based on a direct study of elastic properties rather than using a molecular hypothesis. These equations are more general than Navier's. In Cauchy's theory, and in much of what follows, the aether is supposed to have the same inertia in each medium, but different elastic properties.

1828  -  Poisson shows that the equations of Navier and Cauchy have wave solutions of two types: transverse and longitudinal. Mathematical physicists spend the next 50 years trying to invent an elastic aether for which the longitudinal waves are absent.

1831  -  Faraday shows that changing currents in one circuit induce currents in a neighboring circuit. Over the next several years he performs hundreds of experments and shows that they can all be explained by the idea of changing magnetic flux. No mathematics is involved, just picture thinking using his field-lines.

1831  -  Ostrogradsky rediscovers the divergence theorem of Lagrange, Gauss, and Green. Principles of electromagnetism induction, generation and transmission discovered (Michael Faraday).

1832  -  Joseph Henry independently discovers induced currents.

1833  -  Faraday begins work on the relation of electricity to chemistry. In one of his notebooks he concludes after a series of experiments, ``...there is a certain absolute quantity of the electric power associated with each atom of matter.''

1834  -  Faraday discovers self inductance.

1834  -  Jean Charles Peltier discovers the flip side of Seebeck's thermoelectric effect. He finds that current driven in a circuit made of dissimilar metals causes the different metals to be at different temperatures.

1834  -  Emil Lenz formulates his rule for determining the direction of Faraday's induced currents. In its original form it was a force law rather than an induced emf law: ``Induced currents flow in such a direction as to produce magnetic forces that try to keep the magnetic flux the same.'' So Lenz would predict that if you try to push a conductor into a strong magnetic field, it will be repelled. He would also predict that if you try to pull a conductor out of a strong magnetic field that the magnetic forces on the induced currents will oppose the pull.

1835  -  James MacCullagh and Franz Neumann extend Cauchy's theory to crystalline media

1837  -  Faraday discovers the idea of the dielectric constant.

1837  -  George Green attacks the elastic aether problem from a new angle. Instead of deriving boundary conditions between different media by finding which ones give agreement with the experimental laws of optics, he derives the correct boundary conditions from general dynamical principles. This advance makes the elastic theories not quite fit with light.

1838  -  Faraday shows that the effects of induced electricity in insulators are analogous to induced magnetism in magnetic materials. Those more mathematically inclined immediately appropriate Poisson's theory of induced magnetism

1838  -  Faraday discovers  Faraday's dark space , a dark region in a glow discharge near the negative electrode.

1839  -  James MacCullagh invents an elastic aether in which there are no longitudinal waves. In this aether the potential energy of deformation depends only on the rotation of the volume elements and not on their compression or general distortion. This theory gives the same wave equation as that satisfied by in Maxwell's theory.

1839  -  William Thomson (Lord Kelvin) removes some of the objections to MacCullagh's rotation theory by inventing a mechanical model which satisfies MacCullagh's energy of rotation hypothesis. It has spheres, rigid bars, sliding contacts, and flywheels. First fuel cell.

1839  -  Cauchy and Green present more refined elastic aether theories, Cauchy's removing the longitudinal waves by postulating a negative compressibility, and Green's using an involved description of crystalline solids.

1841  -  Michael Faraday is completely exhausted by his efforts of the previous 2 decades, so he rests for 4 years.

1841  -  James Prescott Joule shows that energy is conserved in electrical circuits involving current flow, thermal heating, and chemical transformations.

1842  -  F. Neumann and Matthew O'Brien suggest that optical properties in materials arise from differences in the amount of force that the particles of matter exert on the aether as it flows around and between them.

1842  -  Julius Robert Mayer asserts that heat and work are equivalent. His paper is rejected by  Annalen der Physik .

1842  -  Joseph Henry rediscovers the result of F. Savery about the oscillation of the electric current in a capacitive discharge and states, ``The phenomena require us to admit the existence of a principal discharge in one direction, and then several reflex actions backward and forward, each more feeble than the preceding, until equilibrium is restored.''

1842  -  Christian Doppler gives the theory of the Doppler effect.

1845  -  Faraday quits resting and discovers that the plane of polarization of light is rotated when it travels in glass along the direction of the magnetic lines of force produced by an electromagnet (Faraday rotation).

1845  -  Franz Neumann uses (i) Lenz's law, (ii) the assumption that the induced emf is proportional to the magnetic force on a current element, and (iii) Ampere's analysis to deduce Faraday's law. In the process he finds a potential function from which the induced electric field can be obtained, namely the vector potential (in the Coulomb gauge), thus discovering the result which Maxwell wrote.

1846  -  George Airy modifies MacCullagh's elastic aether theory to account for Faraday rotation.

1846  -  Faraday, inspired by his discovery of the magnetic rotation of light, writes a short paper speculating that light might electro-magnetic in nature. He thinks it might be transverse vibrations of his beloved field lines.

1846  -  Faraday discovers diamagnetism. He sees the effect in heavy glass, bismuth, and other materials.

1846  -  Wilhelm Weber combines Ampere's analysis, Faraday's experiments, and the assumption of Fechner that currents consist of equal amounts of positive and negative electricity moving opposite to each other at the same speed to derive an electromagnetic theory based on forces between moving charged particles. This theory has a velocity-dependent potential energy and is wrong, but it stimulates much work on electromagnetic theory which eventually leads to the work of Maxwell and Lorenz. It also inspires a new look at gravitation by William Thomson to see if a velocity-dependent correction to the gravitational energy could account for the precession of Mercury's perihelion.

1846  -  William Thomson shows that Neumann's electromagnetic potential is in fact the vector potential from which may be obtained.

1847  -  Weber proposes that diamagnetism is just Faraday's law acting on molecular circuits. In answering the objection that this would mean that everything should be diamagnetic he correctly guesses that diamagnetism is masked in paramagnetic and ferromagnetic materials because they have relatively strong permanent molecular currents. This work rids the world of magnetic fluids.

1847  -  Hermann von Helmholtz writes a memoir ``On the Conservation of Force'' which emphatically states the principle of conservation of energy: ``Conservation of energy is a universal principle of nature. Kinetic and potential energy of dynamical systems may be converted into heat according to definite quantitative laws as taught by Rumford, Mayer, and Joule. Any of these forms of energy may be converted into chemical, electrostatic, voltaic, and magnetic forms.'' He reads it before the Physical Society of Berlin whose older members regard it as too speculative and reject it for publication in  Annalen der Physik .

1848-9  -  Gustav Kirchoff extends Ohm's work to conduction in three dimensions, gives his laws for circuit networks, and finally shows that Ohm's ``electroscopic force'' which drives current through resistors and the old electrostatic potential of Lagrange, Laplace, and Poisson are the same. He also shows that in steady state electrical currents distribute themselves so as to minimize the amount of Joule heating.

1849  -  A. Fizeau repeats Galileo's hilltop experiment (9 km separation distance) with a rapidly rotating toothed wheel and measures m/s.

1849  -  George Gabriel Stokes studies diffraction around opaque bodies both theoretically and experimentally and shows that the vibration of aether particles are executed at right angles to the plane of polarization. Three years later he comes to the same conclusion by applying aether theory to light scattered from the sky. This result is, however, inconsistent with optics in crystals.

ca. 1850  -  Stokes overcomes some of the difficulties with crystals by turning Cauchy's hypothesis around and letting the elastic properties of the aether be the same in all materials, but allowing the inertia to differ. This gives rise to the conceptual difficulty of having the inertia be different in different directions (in anisotropic crystals).

ca. 1850  -  Jean Foucault improves on Fizeau's measurement and uses his apparatus to show that the speed of light is less in water than in air.

1850  -  Stokes law is stated without proof by Lord Kelvin (William Thomson). Later Stokes assigns the proof of this theorem as part of the examination for the Smith's Prize. Presumably, he knows how to do the problem. Maxwell, who was a candidate for this prize, later remembers this problem, traces it back to Stokes and calls it Stokes theorem.

1850  -  William Thomson (Lord Kelvin) invents the idea of magnetic permeability and susceptibility, along with the separate concepts.

1851  -  Thomson gives a general theory of thermoelectric phenomena, describing the effects seen by Seebeck and Peltier.

1853  -  Thomson uses Poisson's magnetic theory to derive the correct formula for magnetic energy: He also gives the formula and gives the world the powerful, but confusing, analysis where the forces on circuits are obtained by taking either the positive or negative gradient of the magnetic energy. Knowing which sign to use is, of course, the confusing part.

1853  -  Thomson gives the theory of the RLC circuit providing a mathematical description for the observations of Henry and Savery.

1854  -  Faraday clears up the problem of disagreements in the measured speeds of signals along transmission lines by showing that it is crucial to include the effect of capacitance.

1854  -  Thomson, in a letter to Stokes, gives the equation of telegraphy ignoring the inductance: where  R  is the cable resistance and where  C  is the capacitance per unit length. Since this is the diffusion equation, the signal does not travel at a definite speed.

1855  -  Faraday retires, living quietly in a house provided by the Queen until his death in 1867.

1855  -  James Clerk Maxwell writes a memoir in which he attempts to marry Faraday's intuitive field line ideas with Thomson's mathematical analogies. In this memoir the physical importance of the divergence and curl operators for electromagnetism first become evident.

1857  -  Gustav Kirchoff derives the equation of telegraphy for an aerial coaxial cable where the inductance is important and derives the full telegraphy equation: where  L  and  C  are the inductance per unit length and the capacitance per unit length. He recognizes that when the resistance is small, this is the wave equation with propagation speed, which for a coaxial cable turns out to be very close to the speed of light. Kirchoff notices the coincidence, and is thus the first to discover that electromagnetic signals can travel at the speed of light.

1861  -  Bernhard Riemann develops a variant of Weber's electromagnetic theory which is also wrong.

1861  -  Maxwell publishes a mechanical model of the electromagnetic field. Magnetic fields correspond to rotating vortices with idle wheels between them and electric fields correspond to elastic displacements, hence displacement currents. This addition completes Maxwell's equations and it is now easy for him to derive the wave equation exactly as done in our textbooks on electromagnetism and to note that the speed of wave propagation was close to the measured speed of light.

Maxwell writes, ``We can scarcely avoid the inference that light in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena.

Thomson, on the other hand, says of the displacement current, ``(it is a) curious and ingenious, but not wholly tenable hypothesis.''

1864  -  Maxwell reads a memoir before the Royal Society in which the mechanical model is stripped away and just the equations remain. He also discusses the vector and scalar potentials, using the Coulomb gauge. He attributes physical significance to both of these potentials. He wants to present the predictions of his theory on the subjects of reflection and refraction, but the requirements of his mechanical model keep him from finding the correct boundary conditions, so he never does this calculation.

1867  -  Stokes performs experiments that kill his own anisotropic inertia theory.

1867  -  Joseph Boussinesq suggests that instead of aether being different in different media, perhaps the aether is the same everywhere, but it interacts differently with different materials, similar to the modern electromagnetic wave theory.

1867  -  Riemann proposes a simple electric theory of light in which Poisson's equation is replaced.

1867  -  Ludwig Lorenz develops an electromagnetic theory of light in which the scalar and vector potentials, in retarded form, are the starting point. He shows that these retarded potentials each satisfy the wave equation and that Maxwell's equations for the field potentials. His vector potential does not obey the Coulomb gauge, however, but another relation now known as the Lorenz gauge. Although he is able to derive Maxwell's equations from his retarded potentials, he does not subscribe to Maxwell's view that light involves electromagnetic waves in the aether. He feels, rather, that the fundamental basis of all luminous vibrations is electric currents, arguing that space has enough matter in it to support the necessary currents.

1868  -  Maxwell decides that giving physical significance to the scalar and vector potentials is a bad idea and bases his further work on light.

1869  -  Maxwell presents the first calculation in which a dispersive medium is made up of atoms with natural frequencies. This makes possible detailed modeling of dispersion with refractive indices having resonant denominators.

1869  -  Hittorf finds that cathode rays can cast a shadow.

1870  -  Helmholtz derives the correct laws of reflection and refraction from Maxwell's equations by using the following boundary condition. Once these boundary conditions are taken Maxwell's theory is just a repeat of MacCullagh's theory. The details were not given by Helmholtz himself, but appear rather in the inaugural dissertation of H. A. Lorentz.

1870-1900  -  The hunt is on for physical models of the aether which are natural and from which Maxwell's equations can be derived. The physicists who work on this problem include Maxwell, Thomson, Kirchoff, Bjerknes, Leahy, Fitz Gerald, Helmholtz, and Hicks.

1872  -  E. Mascart looks for the motion of the earth through the aether by measuring the rotation of the plane of polarization of light propagated along the axis of a quartz crystal.

1873  -  Maxwell publishes his  Treatise on Electricity and Magnetism , which discusses everything known at the time about electromagnetism from the viewpoint of Faraday. His own theory is not very thoroughly discussed, but he does introduce his electromagnetic stress tensor in this work, including the accompanying idea of electromagnetic momentum.

1875  -  John Kerr shows that ordinary dielectrics subjected to strong electric fields become double refracting, showing directly that electric fields and light are closely related.

1876  -  Henry Rowland performs an experiment inspired by Helmholtz which shows for the first time that moving electric charge is the same thing as an electric current.

1876  -  A. Bartoli infers the necessity of light pressure from thermal arguments, thus beginnning the exploration of the connection between electromagnetism and thermodynamics.

1878  -  Edison Electric Light Co. (US) and American Electric and Illuminating (Canada) founded.

1879  -  J. Stefan discovers the Stefan-Boltzmann law, i.e., that radiant emission is proportional.

1879  -  Edwin Hall performs an experiment that had been suggested by Henry Rowland and discovers the Hall effect, including its theoretical description by means of the Hall term in Ohm's law.

1879  -  Sir William Crookes invents the radiometer and studies the interaction of beams of cathode ray particles in vacuum tubes. First commercial power station opens in San Francisco, uses Charles Brush generator and arc lights. First commercial arc lighting system installed, Cleveland, Ohio. Thomas Edison demonstrates his incandescent lamp, Menlo Park, New Jersey.

1879  -  Ludwig Boltzmann uses Hall's result to estimate the speed of charge carriers (assuming that charge carriers are only of one sign.)

1880  -  Rowland shows that Faraday rotation can be obtained by combining Maxwell's equations and the Hall term in Ohm's law, assuming that displacement currents are affected in the same way as conduction currents.

1881  -  J. J. Thomson attempts to verify the existence of the displacement current by looking for magnetic effects produced by the changing electric field made by a moving charged sphere.

1881  -  George Fitz Gerald points out that J. J. Thomson's analysis is incorrect because he left out the effects of the conduction current of the moving sphere. Including both currents makes the separate effect of the displacement current disappear.

1881  -  Helmholtz, in a lecture in London, points out that the idea of charged particles in atoms can be consistent with Maxwell's and Faraday's ideas, helping to pave the way for our modern picture of particles and fields interacting instead of thinking about everything as a disturbance of the aether, as was popular after Maxwell.

1881  -  Albert Michelson and Edwin Morley attempt to measure the motion of the earth through the aether by using interferometry. They find no relative velocity. Michelson interprets this result as supporting Stokes hypothesis in which the aether in the neighborhood of the earth moves at the earth's velocity.

1883  -  Fitz Gerald proposes testing Maxwell's theory by using oscillating currents in what we would now call a magnetic dipole antenna (loop of wire). He performs the analysis and discovers that very high frequencies are required to make the test. Later that year he proposes obtaining the required high frequencies by discharging a capacitor into a circuit.

1883-5  -  Horace Lamb and Oliver Heaviside analyze the interaction of oscillating electromagnetic fields with conductors and discover the effect of skin depth.

1884  -  John Poynting shows that Maxwell's equations predict that energy flows through empty space with the energy flux. He also investigates energy flow in Faraday fashion by assigning energy to moving tubes of electric and magnetic flux.

1884  -  Heinrich Hertz asserts that made by charges and made by a changing magnetic field are identical. Working from dynamical ideas based on this assumption and some of Maxwell's equations, Hertz is able to derive the rest of them.

1887  -  Svante Arrhenius deduces that in dilute solutions electrolytes are completely dissociated into positive and negative ions.

1887  -  Hertz finds that ultraviolet light falling on the negative electrode in a spark gap facilitates conduction by the gas in the gap.

1888  -  R. T. Glazebrook revives one of Cauchy's wave theories and combines it with Stokes anisotropic aether inertia theory to get agreement with the experiments of Stokes in 1867.

1888  -  Hertz discovers that oscillating sparks can be produced in an open secondary circuit if the frequency of the primary is resonant with the secondary. He uses this radiator to show that electrical signals are propagated along wires and through the air at about the same speed, both about the speed of light. He also shows that his electric radiations, when passed through a slit in a screen, exhibit diffraction effects. Polarization effects using a grating of parallel metal wires are also observed.

1888  -  Roentgen shows that when an uncharged dielectric is moved at right angles to a magnetic field is produced.

1889  -  Hertz gives the theory of radiation from his oscillating spark gap.

1889  -  Oliver Heaviside finds the correct form for the electric and magnetic fields of a moving charged particle, valid for all speeds  v  <  c .

1889  -  J. J. Thomson shows that Canton's effect (1762) in which a red hot poker can neutralize the electrification of a small charged body is due to electron emission causing the air between the poker and the body to become conducting.

1890  -  Fitz Gerald uses the retarded potentials of L. Lorenz to calculate electric dipole radiation from Hertz's radiator.

1892  -  Oliver Lodge performs experiments on the propagation of light near rapidly moving steel disks to test Stokes hypothesis that moving matter drags the aether with it. No such effect is observed.

1892  -  Hendrik Anton Lorentz presents his electron theory of electrified matter and the aether. This theory combines Maxwell's equations, with the source terms and with the Lorentz force law for the acceleration of charged particles: Lorentz's aether is simply space endowed with certain dynamical properties. Lorentz gives the modern theory of dielectrics involving and also includes the effect of magnetized matter.

He also gives what we now call the Drude-Lorentz harmonic oscillator model of the index of refraction. But Lorentz's theory has a ``stationary aether'', which conflicts with the negative Michelson-Morley result.

1892  -  George Fitz Gerald proposes length contraction as a way to reconcile Lorentz's theory and the null results on the motion of the earth through the aether. At the end of this year Lorentz endorses this idea.

1894  -  J. J. Thomson measures the speed of cathode rays and shows that they travel much more slowly than the speed of light. The aether model of cathode rays begins to die.

1894  -  Philip Lenard studies the penetration of cathode rays through matter.

1895  -  Pierre Curie experimentally discovers Curie's law for paramagnetism and also shows that there is no temperature effect for diamagnetism.

1895  -  Lorentz, in his ``Search for a theory of electrical and optical effects in moving bodies'' gives the Lorentz transformation to first order in  v / c . The transformed time variable he calls ``local time''.

1895  -  Wilhelm Roentgen discovers X-rays produced by bremsstrahlung in cathode ray tubes.

1896  -  Arthur Shuster, Emil Wiechert, and George Stokes propose that X-rays are aether waves of exceedingly small wavelength.

1896  -  J. J. Thomson discovers that materials through which X-rays pass are rendered conducting.

1896  -  Henri Becquerel discovers that some sort of natural radiation from uranium salts can expose a photographic plate wrapped in thick black paper.

1896  -  P. Zeeman discovers the splitting of atomic line spectra by a magnetic field.

1896  -  Lorentz gives an electron theory of the Zeeman effect.

1897  -  J. J. Thomson argues that cathode rays must be charged particles smaller in size than atoms (Emil Wiechert made the same suggestion independently in this same year). In response Fitz Gerald suggests that ``we are dealing with free electrons in these cathode rays.''

1897  -  W. Wien discovers that positively-charged moving particles can also be made (the so-called  canal rays  of E. Goldstein) and that they have a much smaller  q / m  ratio than cathode rays.

1897  -  J. J. Thomson deflects cathode rays by crossed electric and magnetic fields and measures  e / m .

1898  -  Marie and Pierre Curie separate from pitchblende two highly radioactive elements which they name polonium and radium.

1899  -  Ernest Rutherford discovers that the rays from uranium come in two types, which he calls alpha and beta radiation.

1900  -  Marie and Pierre Curie show that beta rays and cathode rays are identical.

1900  -  Emil Wiechert shows that simply replacing the distributed charge from Lorentz's theory with the charge of a moving point particle gives incorrect results. Instead the Lienard-Wiechert retarded potentials must be used.

1900  -  Joseph Larmor obtains the second order corrections to the Lorentz Transformation.

1901  -  R. Blondlot performs experiments that show that Lorentz's theory in which there is no moving aether gives the correct result in cases where the hypothesis of a moving aether gives the wrong result.

1902  -  Lord Rayleigh performs experiments to test whether the Fitz Gerald contraction is capable of causing double refraction in moving transparent substances. No such effect is found.

1903  -  The Hagen-Rubens connections between the conductivity of metals and their optical properties are experimentally established.

1903  -  Lorentz gives the famous square root formulas for the Lorentz transformation giving the effect to all orders in  v / c .

1904  -  Lorentz gives his electron-collision theory of electrical conduction

1905  -  H. A. Wilson performs experiments similar to those of Blondlot; again, Lorentz's theory is found to give the correct result.

1905  -  Albert Einstein completes Lorentz's work on space-time transformations and relativity is born.

1906  -  Ilchester, Maryland; Fully submerged hydroelectric plant built inside Ambursen Dam.

1907  -  Lee De Forest invented the electric amplifier.

1909  -  First pumped storage plant (Switzerland).

1910  -  Ernest R. Rutherford measured the distribution of an electric charge within the atom.

1911  -  Air conditioning. R. D. Johnson invents differential surge tank and Johnson hydrostatic penstock valve.

1913  -  Electric refrigerator. Robert Millikan measured the electric charge on a single electron.

1920  -  First U.S. station to only burn pulverized coal. Federal Power Commission (FPC).

1922  -  Connecticut Valley Power Exchange (CONVEX) starts, pioneering interconnection between utilities.

1928  -  Construction of Boulder Dam begins. Federal Trade Commission begins investigation of holding companies.

1933  -  Tennessee Valley Authority (TVA) established.

1935  -  Public Utility Holding Company Act. Federal Power Act. Securities and Exchange Commission. Bonneville Power Administration. First night baseball game in major leagues.

1936  -  Highest steam temperature reaches 900 degrees Fahrenheit vs. 600 degrees Fahrenheit in early 1920s. 287 Kilovolt line runs 266 miles to Boulder (Hoover) Dam. Rural Electrification Act.

1947  -  Transistor invented.

1953  -  First 345 Kilovolt transmission line. First nuclear power station ordered.

1954  -  First high voltage direct current (HVDC) line (20 megawatts/1900 Kilovolts, 96 Km). Atomic Energy Act of 1954 allows private ownership of nuclear reactors.

1963  -  Clean Air Act.

1965  -  Northeast Blackout.

1968  -  North American Electric Reliability Council (NERC) formed.

1969  -  National Environmental Policy Act of 1969.

1970  -  Environmental Protection Agency (EPA) formed. Water and Environmental Quality Act. Clean Air Act of 1970.

1972  -  Clean Water Act of 1972.

1975  -  Brown's Ferry nuclear accident.

1977  -  New York City blackout. Department of Energy (DOE) formed.

1978  -  Public Utilities Regulatory Policies Act (PURPA) passed, ends utility monopoly over generation. Power Plant and Industrial Fuel Use Act limits use of natural gas in electric generation (repealed 1987).

1979  -  Three Mile Island nuclear accident.

1980  -  First U.S. windfarm. Pacific Northwest Electric Power Planning and Conservation Act establishes regional regulation and planning.

1981  -  PURPA ruled unconstitutional by Federal judge.

1982  -  U.S. Supreme Court upholds legality of PURPA in FERC v. Mississippi (456 US 742).

1984  -  Annapolis, N.S., tidal power plant-first of its kind in North America (Canada).

1985  -  Citizens Power, first power marketer, goes into business.

1986  -  Chernobyl nuclear accident (USSR).

1990  -  Clean Air Act amendments mandate additional pollution controls.

1992  -  National Energy Policy Act.

1997  -  ISO New England begins operation (first ISO). New England Electric sells power plants (first major plant divestiture).

1998  -  California opens market and ISO. Scottish Power (UK) to buy Pacificorp, first foreign takeover of US utility. National (UK) Grid then announces purchase of New England Electric System.

1999  -  Electricity marketed on Internet. FERC issues Order 2000, promoting regional transmission.

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Early History of Electricity

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The discovery of Electricity

Jul 26, 2014

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The discovery of Electricity. It change our world so much, many progresses were made just because of it . Hence, we have to Remember it forever ever…. By: Yaqi Yang, Xinyao Zhang, Jinxin Chen.

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The discovery of Electricity It change our world so much, many progresses were made just because of it . Hence, we have to Remember it forever ever… By: Yaqi Yang, Xinyao Zhang, Jinxin Chen

Before people know something about electricity. People first noticed the Static Electricity.

Miletusis the first person that recognized the electricity ( era before the sixth century). He used clothes to rub againstaamber, and then observed that the amber attracted some feather. But the scientificstudy of the static electricity is started in the 17th century.

At the beginning of 1600, an English doctor, William Gilbert(1540-1603) said that the force from rubbing is different from the force between ferric matter and magnet. The magnet can only attract ferric matter, but the force between rubbing two stuffs can attract all small and light things. Since that, Gilbert named the object likes the amber as “Electrica”.

A Frenchman called Charles Francois du Fayis the first person who discovered the static electricityin-depth. He had done a great deal of experiments and found out that almost all kinds of matters could used to make electricity when rubbing them. And he denied the idea from Gilbert that matters made up of Electica and non-electica. Furthermore, he found out that the electricity is separated into two forms which he called resinous (-) and vitreous (+), now called negative and positive.

These three people played an important part in the development of static electricity in Europe. Also, these discoveries attracted Benjamin Franklin’s attention later on. Then…

The first contribution of Benjamin Franklin is to discover the “electric current”. He think that electricity is a no weight fluid and exist in all the objects. If an object receives more charge than normal, it was named as positive current; if an object receives less charge than normal, it was called as negative current. According to Franklin, electricity which always move is from positive to negative. However, this idea is totally opposite to what we believe today!

Franklin’s another contribution to electricity is the famous “kite experiment” in 1752. This experiment providesthatlightingiselectricity. He used a metal wire with a keyto connect a kite andfly it in the sky. Then, Franklin held thekite in one hand and used the other hand to touch the key.He felt a strong impact while he saw the sparks between the key and his finger. After he touched the electricity, he spent years work on it, and invented the first lighting conductor. However, this was just a start . . .

who is the first scientist studiedthe electric current? Italian’s anatomist Luigi Galvani who was considered the first people who studiedthe electric current.

P.S. A famous experiment made by Galvani Galvani’s discovery is coincidental, the ordinary lightning phenomenon in 1780 lead to his thinking. According to popular version of the story, Galvani put a frog at a table in his dissecting room where he once taken the static electricity. He then use a scalpel which had picked up a charge and then touch the frog’s leg, this lightning cause the sparks of frog’s leg. It is so surprise that the frog’s leg kick as if it is alive. He use total 12 years to study the electrical effects in muscles like the frog’s leg. Finally, he discover that if nerve and muscle connected by the two different metals, like iron and steel wire, the frog’s leg will got spasm and spark. This phenomenon was caused by the current loop. Muscle and two different metal wires consist of the first current loop in the world.

According to this phenomenon, he created the “Galvani Battery”. Galvani could not explain the reason of the electric current phenomenon which he named the term animal electricity.

Galvani called the term animal electricity to describe the force that activated themuscles of his specimens. Along with contemporaries, he regarded their activation as being generated by an electrical fluid that is carried to the muscles by thenerves. The phenomenon was dubbedgalvanism, after Galvani, on the suggestion of his peer and sometime intellectual adversaryAlessandro Volta. Today, the study of galvanic effects in biology is calledelectrophysiology, the term galvanism being used only in historical contexts. （words in red are all from WIKI, is a supplement of what we write about the experiment. Just a reference.)

Another Italian scientist Alessandro Volta disagreed with the Galvani’s idea. Under the opinion of himself, Volta created the famous “Volta Battery”. This is only an original battery which is a battery pack connected by a lot of zinc batteries . The creation of Volta makes people receive the continuous current controlled by human, and lay the foundation of studying the electric current.

Up till now, human is really familiarto the electricity . . . Many masterpieces were given birth to by scientists by using the knowledge of electricity.

How the discovery of the Electricity influence the world?

No.1 In the field of science: Chemistry … Just due to the battery, HumphryDavy,a,English chemist, could lay the foundation of the Arrhenius ionization theory and separated sodium, potassium, strontium, boron, calcium, chlorine, fluorine, iodine and other elements. What’s more, Michael Faraday, Humphry’s assistant, created the Faraday's laws of electrolysis. These really leaded the chemistry into a new world!

No.2In the field of science: Physics… The study of electricity is a significant step for people to do more studies on electromagnetic phenomena in the future.

Due to the foundation of the electricity, Hans Christian Oersted, Danish physicist and chemist, could have a chance to find the magnetic effect of current in 1820 . After that, in 1824, D.F.J.found electromagnetic damping and Electromagnetic drive after many experiments. And, these two phenomenaare well known as the earliest electromagnetism induction phenomena

Michael Faraday, English physicist, concluded all the phenomena from his experiments and called named “electromagnetic induction”. After that “Generators” come to truth. This contribution changed our world in a significant way!

No.3 In our daily life … Current is the charge to move in a certain direction. When the current go through the circuit, it will generate many new effects. For instance, if the current go through the light bulb, it may light bulb; if the current go through the fan, the fan runs. Moreover, current can charge the battery. All these phenomena show that the current flow is a kind of energy transfer process, energy can be transformed through a variety of specific devices for other forms of energy.

For example, because of electricity, people later created electric appliance: 1. Electric lights—with it, we no longer need to live in dark at night. People also createddifferent kinds of electric lights from tiny ones to giant ones to fit different demands. They are really helpful !!! Also, electric light became a symbol that people came into the Electric Age. Oh, look! Even an age is named after “ Electric” ! 2. Fans, air conditioners, vacuum cleaners, televisions, wash machines, etc—with them, we can enjoy our colorful life!!! 3. In today’s life, nearly all equipments used not only in home, but also in building sites，factories, labs, need electricity!!! Without electricity, our world cannot makes progress！

All the information are from website: Google.com WIKI baidu. com We learned from them and used those knowledge to finish this project.

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