Who discovered electricity? The surprising answer is: nobody did, at least not alone. Electricity was always there, in lightning and in the crackle when you pull off a woolly jumper.
What people discovered, bit by bit, was how electricity works and how to use it. It took about 2,600 years and many curious minds. Let’s meet them one by one!
Where does the word “electricity” come from?
About 2,600 years ago, a Greek thinker named Thales lived in the city of Miletus. He is said to have noticed something strange about amber. Amber is golden and see-through. It is tree resin, a sticky tree juice, that hardened over millions of years.
When amber is rubbed with fur or wool, it starts to pull in dust, bits of straw and feathers. Today we know why. Rubbing moves tiny particles called electrons from one thing to the other. This leaves both things with an electric charge, and charged things pull and push on each other.
The Greek word for amber was ēlektron. That is where our words electricity and electron come from!
We cannot be sure that Thales really did this, though. None of his own writings survive. The story comes from people who lived long after him.
Who first studied electricity like a scientist?
For about 2,000 years, people learned little more about electricity. Then, in 1600, an English doctor named William Gilbert wrote a big book about magnets and amber. He later became the doctor of Queen Elizabeth I.
Gilbert tested many materials by rubbing them, like glass, sulfur and precious stones. Many of them pulled in light things, just like amber. He called them “electrics”, a word based on the old name for amber.
He also showed that the whole Earth is like a giant magnet. That is why a compass needle points north.
Can electricity travel and be stored?
In 1729, Stephen Gray in England found that electricity can travel a long way along a thread. But it would not travel along silk. This is how people first learned the difference between conductors and insulators: materials that let electricity through, and materials that stop it.
Around 1745, people learned to store electricity in a special glass jar, called a Leyden jar. A charged jar could give a big spark and a painful shock.
Is lightning electricity?
Benjamin Franklin was an American printer, writer and scientist. Later, he also helped to found the United States. He noticed that sparks and lightning have a lot in common. Both are bright, fast and noisy, and both zigzag through the air.
So Franklin guessed that lightning is a giant electric spark. He also gave us the words positive and negative (plus and minus) for the two kinds of electric charge.
In the famous story, Franklin flew a kite in a thunderstorm in June 1752. A metal key hung on the wet kite string. When he brought his knuckle near the key, a small spark jumped. This seemed to prove that storm clouds are full of electricity.
The kite was not struck by lightning, which would probably have killed him. Historians are not sure exactly what happened, because Franklin described it only briefly, months later. But in France, other scientists followed his ideas and really did draw sparks from a storm cloud.
Franklin also invented the lightning rod: a metal rod on a roof, joined to the ground by a thick wire. It leads lightning safely into the ground, so the house does not catch fire.
Go deeper: What really happened with the kite? for grown-ups and the extra curious
- Franklin first proposed catching electricity from storm clouds with a tall, pointed iron rod set up on a high place. The kite came later.
- The iron-rod experiment was done first in France, at Marly-la-Ville, on 10 May 1752.
- Franklin’s own report of the kite appeared in the Pennsylvania Gazette on 19 October 1752. It explained how to do the experiment, with the string held by a dry silk ribbon under cover and the charge collected from the key into a Leyden jar. It did not say when he had done it himself.
- The June 1752 date and the other details come from Joseph Priestley’s book The History and Present State of Electricity (1767). Priestley probably heard them from Franklin himself. According to Priestley, Franklin’s son William helped him.
- The kite was not hit by lightning. The storm cloud’s electric field charged the kite and the wet string, and the charge could be drawn off at the key.
- Most historians accept that the kite experiment happened, even though its details are uncertain. A few, such as Tom Tucker in Bolt of Fate (2003), have argued that it may never have taken place.
Why did the frog legs twitch?
Around 1780, the Italian doctor Luigi Galvani was experimenting with frogs in the city of Bologna. He noticed that the legs of dead frogs twitched when a spark flew nearby. Later, he saw them twitch when they were touched with pieces of metal.
Galvani thought that animals make their own electricity. He called it “animal electricity”. He was partly right: your nerves really do send tiny electric signals to your muscles.
Another Italian scientist, Alessandro Volta, had a different idea. He noticed that the frog legs twitched best when two different metals touched them. Perhaps the electricity came from the metals, not from the frog?
Who built the first battery?
To test his idea, Volta left out the frogs. He stacked up discs of zinc and copper, with cardboard soaked in salty water between them. He repeated the layers again and again, making a tall pile. In 1800, he announced that his pile made electricity flow through a wire joining its top and bottom.
This “pile” was the first battery. A spark is over in a flash, but the pile gave a steady flow that kept going. That flow is what we call an electric current.
Volta became famous. In 1801, he showed his battery to Napoleon, the ruler of France. Today the unit of voltage, the volt, is named after him.
Can electricity move a magnet?
A compass needle is a tiny magnet that always turns to point north. In 1820, the Danish scientist Hans Christian Ørsted noticed something amazing. When electricity flowed through a wire near a compass, the needle swung away from north!
This showed that electricity and magnetism are connected. An electric current can push a magnet, even without touching it.
Within weeks, the French scientist André-Marie Ampère was doing experiments of his own. He showed that two wires carrying currents pull toward each other or push each other away, like magnets. The unit of current, the ampere (amp for short), is named after him.
Who measured the push and the flow?
Georg Ohm was a German schoolteacher. He built his own equipment and measured very carefully how much current flows through different wires. In 1827, he published a simple rule: push harder, and more current flows. A long, thin wire holds the current back more than a short, thick one.
This holding back is called resistance, and the rule is known as Ohm’s law. At first, many scientists did not take Ohm seriously. Years later, he won a famous prize for his work. The unit of resistance, the ohm, carries his name.
Can magnets make electricity?
Michael Faraday grew up poor in London. At 14, he started working in a bookshop, sewing and gluing books together. He read the science books that passed through his hands. Later, the famous chemist Humphry Davy made him his assistant.
Ørsted had shown that electricity can move a magnet. Faraday wondered if it also worked the other way round: can a magnet make electricity? In 1831, he found the answer.
When Faraday pushed a magnet into a coil of wire, a current flowed in the wire. When he pulled the magnet out, the current flowed the other way. When the magnet stood still, nothing happened at all.
This discovery changed the world. A machine that keeps spinning magnets past coils of wire makes electricity nonstop. Such a machine is called a generator. Most of the electricity in your home comes from huge generators in power stations.
Ten years earlier, in 1821, Faraday had also built the first machine that used electricity to keep something spinning. It was the great-grandparent of every electric motor.
Go deeper: How a moving magnet makes a current for grown-ups and the extra curious
Faraday discovered electromagnetic induction: a voltage appears in a coil whenever the magnetic field passing through it changes. The faster the change and the more turns of wire, the bigger the voltage:
Here is the voltage made in the coil, is the number of turns, and is how fast the magnetic flux (the amount of magnetic field passing through the coil) changes. The minus sign means that the current pushes back against the change (Lenz’s law).
In a power station, steam, falling water or wind spins a turbine, and the turbine spins the generator. One of the great pioneers of the steam turbine, Aurel Stodola, was born in 1859 in Liptovský Mikuláš, in today’s Slovakia.
What does light have to do with electricity?
James Clerk Maxwell was a Scottish scientist who was brilliant at maths. In the 1860s, he wrote all the known rules of electricity and magnetism as a set of equations. His maths held a surprise: electric and magnetic effects can travel through space as a wave.
Maxwell worked out how fast this wave travels, and the answer was the speed of light! So he concluded that light itself is an electric and magnetic wave. Scientists call it an electromagnetic wave.
His equations also predicted invisible waves of the same kind. In 1887, the German scientist Heinrich Hertz made such waves in his lab. Today we call them radio waves. We use them for radio, TV, Wi-Fi and mobile phones.
Go deeper: How Maxwell found the speed of light for grown-ups and the extra curious
From electric and magnetic measurements alone, Maxwell could calculate the speed of his waves:
Here and are two constants that describe how strong magnetic and electric forces are in empty space. The result matched the measured speed of light. Light, radio waves, microwaves, infrared, ultraviolet light and X-rays are all electromagnetic waves. They differ only in their wavelength.
Who lit up the night?
Electric light for every home needed a light bulb: a glass bulb with a thin thread inside, called a filament. Current heats the thread until it glows. The air is pumped out of the bulb, so the thread does not burn up.
Many inventors tried to make such a bulb, but theirs burned out quickly. In 1879, Thomas Edison’s team in the USA made a bulb with a carbon thread that glowed for more than 13 hours. At about the same time, Joseph Swan in England made a similar bulb. Soon, their bulbs lasted for hundreds of hours.
Edison did not stop at the bulb. In 1882, he opened one of the first power stations, in New York. It sent electricity through wires under the streets to homes and offices.
His electricity flowed in one direction only, like the current from a battery. This is called direct current, or DC.
Which kind of current won?
Nikola Tesla was born in 1856 in a village in today’s Croatia. He studied in Graz and Prague and worked in Budapest and Paris. Then he sailed to New York, where he worked for Edison’s company for a few months.
Tesla believed in a different kind of current: alternating current, or AC. It keeps switching direction, back and forth, many times every second. Tesla invented a clever motor that runs on AC. In 1888, the businessman George Westinghouse bought the rights to it.
Westinghouse’s side and Edison’s side fought hard to win customers. Today this fight is called the war of the currents.
AC had one big advantage. A simple machine called a transformer can raise or lower its voltage easily. So power stations could send AC far away at a very high voltage, with little energy lost on the way. Near homes, transformers lowered the voltage again.
Edison’s DC could only reach homes less than about 1.5 kilometres (one mile) from a power station. But in 1896, AC from a power station at Niagara Falls reached the city of Buffalo, about 40 kilometres away. AC went on to win. Today, almost every home in the world gets AC from its sockets.
Go deeper: Why high voltage saves energy for grown-ups and the extra curious
Wires heat up when current flows through them, and that heat is wasted energy. The power lost in a wire is
where is the current and is the wire’s resistance. The power delivered is . To send the same power at 10 times the voltage, you need only a tenth of the current. The loss then drops to a hundredth!
Transformers only work with AC, because they need a changing magnetic field — Faraday’s induction again. Today, DC is making a comeback. Modern electronics can change DC voltages too, and some very long cables, such as those under the sea, carry high-voltage DC.
What is electricity made of?
By the 1890s, people could make electricity, send it far away and use it. But nobody knew what was actually moving inside the wires!
In 1897, the English scientist J. J. Thomson solved the mystery. He discovered a tiny particle, much smaller than an atom, with a negative electric charge. Today we call it the electron.
Soon, scientists understood that an electric current in a metal wire is a flow of electrons. The story that began with amber, the Greek ēlektron, had led to a particle called the electron!
Go deeper: Franklin’s plus and minus for grown-ups and the extra curious
Franklin had to guess which kind of charge moves when current flows. He guessed that the positive kind flows, from plus to minus. That choice became the standard direction of current, and it is still drawn in circuit diagrams today.
When Thomson found the electron, it turned out that electrons carry the kind of charge Franklin had called negative. So in a metal wire, electrons actually drift from minus to plus, the opposite way to the arrow drawn for current. Both descriptions give the same answers in calculations.
Who sent messages without wires?
Since around 1840, people had sent messages along wires with the telegraph. Each letter was a code of short and long signals, the dots and dashes of Morse code. Around 1900, inventors raced to send such messages through the air with radio waves, without any wires. The most famous of them was Guglielmo Marconi from Italy.
One of those inventors came from Slovakia. Jozef Murgaš was born in 1864 in Tajov, a village near Banská Bystrica. He was a priest and a painter who loved science. In 1896, he moved to Wilkes-Barre in the USA, to work as a priest for Slovak families living there.
Murgaš invented a clever way to send Morse code by radio. Each dot was sent as a high tone and each dash as a low tone, so they were easy to tell apart by ear. In 1904, he received his first American patents: official papers that say who invented something. In 1905, he sent radio messages between two towns about 30 kilometres apart.
Whose names are hiding in your home?
Look at a battery, a light bulb box or a phone charger. You will find units named after scientists and inventors, most of them from this story:
| Unit | What it measures | Named after |
|---|---|---|
| volt (V) | the push of electricity | Alessandro Volta |
| ampere (A) | how much current flows | André-Marie Ampère |
| ohm (Ω) | resistance | Georg Ohm |
| watt (W) | electric power: how much energy is used every second | James Watt, a Scottish engineer |
| hertz (Hz) | how many times something repeats every second | Heinrich Hertz |
The tesla, named after Nikola Tesla, measures how strong a magnetic field is: the invisible pull around a magnet.
Check yourself
Where does the word “electricity” come from?
Show the answer
From the Greek word for amber — The ancient Greeks called amber “ēlektron”. When amber is rubbed, it pulls in dust and feathers.
The ancient Greeks called amber “ēlektron”. When amber is rubbed, it pulls in dust and feathers.
Check yourself
What did Michael Faraday discover in 1831?
Show the answer
That moving a magnet near a coil of wire makes a current flow — Moving a magnet in or out of a coil makes a current flow. Generators in power stations still use this idea.
Moving a magnet in or out of a coil makes a current flow. Generators in power stations still use this idea.