How Humans Discovered Electricity

If you switch on a desk lamp, glance at your phone's battery percentage, or connect to a Wi-Fi router, you are manipulating the fundamental force that holds physical matter together.

Every atom in your body consists of positively charged protons bound in a nucleus, orbited by a cloud of negatively charged electrons. The attraction and repulsion between these charges—the electromagnetic force—is thirty-nine orders of magnitude stronger than gravity:

If the electric charge in your body were unbalanced by just one percent, the repulsive force would blow you apart with enough energy to level an entire mountain range.

Yet for ninety-nine percent of human history, humanity was completely blind to this cosmic engine.

Electricity revealed itself only in baffling, isolated, seemingly magical fragments:

• Rub a piece of fossilized tree resin (amber) with wool on a dry winter day, and it mysteriously lifts dry straw and chicken feathers.
• Reach into the muddy shallows of the Nile, and an electric catfish (Malapterurus electricus) shocks your arm with a violent jolt that leaves your shoulder temporarily paralyzed (ancient Egyptian physicians prescribed these shocks to treat gout and migraines).
• Look into a summer thunderstorm, and a blinding spear of lightning splits an oak tree in half with the roar of a thousand cannons.

Nobody imagined that the feather clinging to amber, the fish in the Nile, and the lightning bolt from Zeus were the exact same physical phenomenon.

The story of how humans figured out what electricity was is one of the greatest detective stories in the history of science:

                     THE FIVE EXPERIMENTAL THRESHOLDS OF ELECTRICITY
  
  1. Amber Friction         2. The Leyden Jar         3. The Voltaic Pile       4. Oersted's Needle       5. Faraday's Induction
    (~600 BCE, Thales)        (1745, Musschenbroek)     (1800, Volta)             (1820, Ørsted)            (1831, Faraday)
    Static surface charge     First capacitor; stores   First battery; creates    Electricity creates       Moving magnet creates
    attracts light feathers   thousands of volts        continuous direct current a magnetic field          continuous electricity

The diagram below traces the five laboratory breakthroughs that transformed an invisible curiosity into the lifeblood of modern civilization:

---

1. Amber and the Invisible Effluvium (~600 BCE–1600 CE)

The story begins around 600 BCE with the Greek philosopher Thales of Miletus.

Thales observed that when a piece of golden-yellow Baltic amber was rubbed vigorously with dry cat fur or sheep’s wool, it developed the power to attract lint, feathers, and dried bits of papyrus. The ancient Greek word for amber was ēlektron (ἤλεκτρον), derived from ēlektōr, meaning "the beaming, radiant sun."

For two thousand years, natural philosophers categorized amber alongside the lodestone—naturally magnetized chunks of iron oxide (magnetite) found in Magnesia in northern Greece, which attracted iron filings.

In 1600, Dr. William Gilbert, personal physician to Queen Elizabeth I, published the first masterwork of experimental electrical physics: De Magnete ("On the Magnet").

               GILBERT'S VERSORIUM: THE FIRST ELECTROSCOPE (1600)
  
                            Lightweight Metallic Needle
                                 ┌──────────────┐
                                 │              │
                       ──────────┴──────▲───────┴──────────
                                        │
                                        │ Pivot Point
                                  ┌─────┴─────┐
                                  │   Base    │
                                  └───────────┘
                                        ▲
                   Amber rubbed with silk brought nearby
                   causes the balanced needle to rotate!

Gilbert built a delicate pivot with a light metallic needle called the versorium (the first electroscope). Using the versorium, Gilbert systematically tested dozens of common substances: glass, sulfur, sealing wax, diamonds, sapphires, rock crystal, and resin.

Gilbert discovered that:

1. Many materials—not just amber—attract lightweight particles when rubbed. Gilbert coined the New Latin word electricus ("of amber" or "amber-like"), from which we get the word electricity.
2. Electricity and Magnetism were fundamentally distinct:
   • A magnet attracts only iron and requires no friction; its power cannot be blocked by water, parchment, or breath.
   • An electric attraction requires friction, attracts almost any lightweight substance, and is instantly quenched by damp air or a thin sheet of paper.

Gilbert hypothesized that rubbing amber released an invisible, heated, subtle vapor—an effluvium—which radiated outward, cooled the surrounding air, and pulled small objects back toward the amber like an invisible elastic web.

---

2. The Leyden Jar: Bottling the Invisible Fire (1745)

Throughout the seventeenth century, experimenters built hand-cranked electrostatic friction machines: large sulfur balls or glass globes spun against leather pads, throwing off bright sparks in darkened rooms.

Yet there was a fatal experimental limitation: you could not store the spark. The moment you stopped cranking the wheel, the electrical charge leaked into the damp air and disappeared.

In late 1745 and early 1746, this barrier was broken independently in two places: first in October 1745 by German cleric and experimenter Ewald Georg von Kleist in Pomerania (who charged a medicine bottle containing a nail), and a few months later at the University of Leiden in the Netherlands by physics professor Pieter van Musschenbroek and his collaborator Andreas Cunaeus. Believing that electricity was an elusive fluid evaporating into the air, Musschenbroek and Cunaeus attempted to trap it inside a glass vessel filled with water:

               THE ANATOMY OF THE LEYDEN JAR (1745)
  
                    Brass Knob & Conducting Rod
                                ▲
                                │
                          ┌─────┴─────┐  Wooden Stopper
                          │ ┌───────┐ │
                          │ │ Water │ │  Inner Conductor (Salty water or tin foil)
     Glass Cylinder ────▶ │ │   +   │ │
    (Dielectric Barrier)  │ │   +   │ │
                          │ └───────┘ │
                          └───────────┘
                          │███████████│  Outer Metal Foil (Connected to Ground)
                          └───────────┘

1. They took a glass jar half-filled with water.
2. They suspended a brass wire from an electrostatic generator down into the water through a cork stopper.
3. While holding the glass bottle in one hand and charging the wire from the friction generator, Cunaeus (and subsequently Musschenbroek) touched the brass conductor with his free hand.

The result was an explosion of physiological agony:

"Suddenly my right hand was struck with such violence that my whole body shook as if hit by lightning... the arm and entire body were affected in so terrible a manner that I cannot express; in a word, I thought my life was at an end." — Pieter van Musschenbroek, letter to René-Antoine Ferchault de Réaumur (January 1746)

Kleist, Cunaeus, and Musschenbroek had accidentally invented the capacitor—a device for storing electrical potential energy in an electrostatic field across an insulator.

How the Leyden Jar Worked Mechanically

The human hand holding the glass bottle served as the grounded outer conductor. The water inside served as the inner conductor. The glass walls of the jar served as the dielectric insulator.

As the friction machine pumped positive charge into the water:

1. Positive charges accumulated inside the bottle.
2. By electrostatic induction, these charges pushed positive charges away from the outside of the glass, leaving the experimenter's hand loaded with negative charge.
3. The thin glass prevented the opposite charges from meeting, creating an intense, concentrated electrostatic field across the glass barrier.
4. When the experimenter touched the top brass wire, his body completed a low-resistance circuit between the inside and outside of the jar. Thousands of volts of accumulated charge slammed through his nervous system in a single microsecond.

The Leyden jar turned electricity into an international sensation. In Paris, royal tutor Abbé Nollet performed a demonstration for King Louis XV at Versailles: he connected nearly two hundred men (First a company of royal guards, and later Carthusian monks) in a long chain using iron wires, discharged a Leyden jar into the line, and watched all of them leap into the air simultaneously, demonstrating that electrical conduction propagates almost instantaneously.

---

3. Benjamin Franklin: The Single Fluid and the Thunderstorm (1752)

In colonial Philadelphia, a retired printer named Benjamin Franklin read about the Leyden jar and transformed electrical theory from carnival parlor tricks into quantitative physics.

Franklin realized that electricity was not multiple different fluids, but a single universal fluid permeating all physical matter:

               FRANKLIN'S SINGLE-FLUID CONSERVATION LAW
  
   Normal Matter (Neutral):      Contains natural equilibrium volume of electrical fluid.
   Excess Fluid (+ Positive):    Matter has gained fluid through friction.   (Vitreal state)
   Deficit Fluid (- Negative):   Matter has lost fluid through friction.     (Resinous state)
  
   Conservation Law:             Electric fluid is neither created nor destroyed;
                                 it is merely transferred from one body to another:
                                         Q_total = constant

Franklin introduced the enduring vocabulary of modern electrical engineering: positive, negative, charge, conductor, armature, and battery (borrowing the artillery term for a row of firing cannons to describe a bank of connected Leyden jars).

From the Sentry-Box Proposal to the Kite in the Thunderstorm (May–June 1752)

Franklin looked at a six-inch blue spark leaping from a Leyden jar. It had a jagged, crooked path, smelled of sulfurous ozone, crackled with a snap, and ignited gunpowder.

Franklin asked: Is lightning merely a gigantic, natural Leyden jar discharge in the sky?

In 1750, Franklin published a specific experimental design—the "sentry-box" experiment—proposing that an insulated iron rod erected atop a tall tower would draw electrical fire down from passing storm clouds. On May 10, 1752, French naturalist Thomas-François Dalibard, following Franklin's published instructions at Marly-la-Ville near Paris, erected a 40-foot insulated iron rod and successfully drew electrical sparks from a thundercloud into a Leyden jar, providing the first experimental proof of Franklin's hypothesis.

Before news of Dalibard's success crossed the Atlantic—and tired of waiting for the steeple of Christ Church in Philadelphia to be completed—Franklin devised a mobile alternative. In June 1752, Franklin and his son William flew a silk kite into the base of an approaching Pennsylvania thundercloud.

• At the top of the kite was a sharp iron wire to draw the electrical charge.
• The flying line was common hemp twine, which became weakly conductive when dampened by rain.
• Near Franklin's hand, he tied a dry silk ribbon (an insulator) and stood under the shelter of a shed to keep the silk dry, suspending a brass house key at the junction between the wet hemp and dry silk.

               FRANKLIN'S KITE EXPERIMENT (PHILADELPHIA, 1752)
  
                           Thundercloud (Negatively Charged)
                                      ☁ ☁ ☁
                                        │
                                        │ Wet Hemp String
                                        │ (Conductor)
                                        ▼
                                 Brass House Key
                                       ( 🗝 )
                                        │
                     Dry Silk Ribbon ───┴─── Hand of Franklin (Insulated)
                                        │
                                        ▼
                          Sparks jump to Franklin's knuckle!

Franklin did not wait for a direct lightning bolt to strike the kite (had a main lightning stroke hit the wet string, it would likely have killed him, as happened a year later in July 1753 to Swedish-German physicist Georg Wilhelm Richmann in Saint Petersburg when a ball of lightning leaped from his ungrounded apparatus to his forehead).

Instead, under the intense electrostatic field beneath the storm cloud, Franklin watched the loose fibers of the hemp twine stand on end by mutual repulsion. He brought his knuckle close to the brass key: a crisp, crackling electric spark jumped from the key to his finger.

He touched the key to an uncharged Leyden jar: the jar charged up with atmospheric electricity. The conclusion verified at Marly-la-Ville and Philadelphia was revolutionary: Lightning was not a supernatural thunderbolt; it was atmospheric electricity governed by the same physical laws as laboratory charges, and buildings could be protected from it using grounded lightning rods.

---

4. Galvani vs. Volta: The War of the Frog's Legs (1780–1800)

By 1780, scientists understood static electricity. But static electricity was useless for practical work. It existed only as a violent, uncontrolled, instantaneous burst—a fractions-of-a-second spark that vanished before you could harness it.

The breakthrough to continuous, controlled electricity began in Bologna, Italy, in the anatomy laboratory of physician Luigi Galvani.

Galvani had dissected a frog, leaving the hind legs attached to the lumbar spine on a glass table near an electrostatic generator.

               GALVANI'S EXPERIMENT: FROG LEGS AND DISSIMILAR METALS
  
                    Brass Hook (Piercing Spinal Cord)
                                │
                          ┌─────┴─────┐
                          │   SPINE   │
                          ├───────────┤
                          │ FROG LEGS │
                          └─────┬─────┘
                                │
                    Iron Trellis / Rail
                                ▲
                 When Brass touches Iron:
                 The dead muscles twitch violently!

While someone was sparking the generator, an assistant touched the exposed inner crural nerve of the frog with a steel scalpel: the dead frog’s legs violently kicked and convulsed as if alive.

Galvani was stunned. Over years of experiments, he discovered that the legs kicked even when the electrostatic generator was completely absent:

• If he hung the frog legs by a brass hook through the spinal cord and pressed the hook against an iron balcony railing, the legs twitched every time the wet muscle swung against the iron.

Galvani published his findings in 1791, declaring that he had discovered "animal electricity":

Living organisms possess an internal bio-electric fluid generated by the brain and stored in the muscles, with the nerves acting as conductors.

Alessandro Volta's Counter-Attack

At the University of Pavia, physicist Alessandro Volta replicated Galvani's work. At first, Volta was captivated. But soon, he noticed a critical anomaly:

The frog's legs only twitched strongly when two different metals were used in the circuit (such as brass and iron, or silver and zinc). When Volta connected the nerve and muscle using a single, uniform loop of pure silver wire, nothing happened.

Volta made a radical intellectual leap: The frog was not the primary source of the metallic current. (Though Galvani later proved that genuine bioelectricity does exist in living nerve tissue even without metals—founding modern electrophysiology—in the bimetallic experiments, the dead frog was acting as a moist, hyper-sensitive biological galvanometer detecting an external current generated by the two dissimilar metals!)

To prove this, Volta performed a famous, slightly grotesque self-experiment:

• He placed a silver coin on top of his tongue and a disc of tin or lead underneath his tongue.
• When he touched the two metals with a wire, he did not feel a muscle spasm; he tasted a sharp, persistent, metallic sour taste (the taste of electric current stimulating acid-sensitive taste receptors).
• When he touched zinc to one eyelid and silver to the roof of his mouth, he saw flashes of light (electrophosphenes).

In the bimetallic circuit, the electricity was being generated by dissimilar metals separated by an ionic electrolyte.

---

5. The Voltaic Pile: The Invention of the Battery (1800)

In late 1799, Volta set out to prove his thesis once and for all. If electricity came from dissimilar metals and a conducting liquid, he didn't need dead frogs at all.

He built a vertical stack of alternating discs of zinc and copper (or zinc and silver), separated by discs of cardboard or leather soaked in salt water (brine) or dilute acid:

               THE VOLTAIC PILE: THE WORLD'S FIRST BATTERY (1800)
  
                        Negative Terminal (-)
                                 │
                    ┌────────────────────────┐  Zinc Disc
                    │░░░░░░░░░░░░░░░░░░░░░░░░│  Cardboard soaked in Salt Water
                    │████████████████████████│  Copper Disc
                    ├────────────────────────┤
                    │                        │  Zinc
                    │░░░░░░░░░░░░░░░░░░░░░░░░│  Brine Cardboard
                    │████████████████████████│  Copper
                    ├────────────────────────┤
                    │                        │  Zinc
                    │░░░░░░░░░░░░░░░░░░░░░░░░│  Brine Cardboard
                    │████████████████████████│  Copper
                    └────────────────────────┘
                                 │
                        Positive Terminal (+)

When Volta connected a wire from the top zinc disc to the bottom copper disc, something historic occurred:

There was no crack, no explosion, and no momentary spark.

Instead, a silent, smooth, steady, continuous flow of electric current coursed through the wire for hours.

The Chemical Mechanism Volta Did Not Understand

Volta believed the electricity came purely from the dry mechanical contact of the two metals (contact tension).

We now know Volta was wrong about the mechanism, though right about the device. The Voltaic pile operated via redox (reduction-oxidation) electrochemical reactions, driven by the difference in half-cell reduction potentials and the decrease in Gibbs free energy (Δ_r G < 0; mechanisms explored in How Chemical Bonds Actually Form and How Chemical Reactions Actually Work):

1. At the Zinc Anode (Oxidation): Zinc atoms give up two electrons and dissolve into the salty electrolyte solution as zinc ions:

2. The Electron Drive: The electrons released on the zinc plate travel through the external wire toward the copper cathode.
3. At the Copper Cathode (Reduction): Protons from water/acid (or dissolved oxygen) in the wet electrolyte accept those electrons at the catalytic copper surface, evolving hydrogen gas bubbles:

Volta had created the first chemical battery (for the full modern electrochemistry of half-cell potentials, the Nernst equation, and lithium-ion intercalation, see How Batteries Convert Chemical Energy into Electrical Energy).

For the first time in human history, electricity ceased to be an uncontrollable lightning flash. It became a tamed, portable, controllable stream of energy operating at steady voltage. The unit of electrical potential—the Volt—is named in his honor.

---

6. Electromagnetism: The Accidental Compass Deflection (1820)

With the Voltaic battery, laboratory scientists around the world could now pass steady currents through liquids, acids, and wires. Chemistry was revolutionized: Humphry Davy used battery currents (electrolysis) to tear apart molten salts and discover new chemical elements: sodium, potassium, calcium, magnesium, barium, strontium, and boron.

Yet electricity and magnetism were still considered two completely separate forces of nature.

In April 1820, during an evening lecture at the University of Copenhagen, Danish professor Hans Christian Ørsted was demonstrating the heating of a platinum wire using a Voltaic battery.

On the lecture bench, lying near the battery wire, happened to be a small magnetic navigation compass.

               OERSTED'S DISCOVERY OF ELECTROMAGNETISM (1820)
  
            Current OFF:                               Current ON:
            Compass points North.                      Compass swings 90° PERPENDICULAR!
  
                     N                                          ▲
                     │                                          │ Current (I)
                     ▲                                          │
                     │                                     ┌────┴────┐
                     │ Needle Points                       │   (•)   │ Needle Swings
                     │ North                               └────┬────┘ Across Wire
                     ▼                                          │
                     │                                          │
                     S

When Ørsted connected the battery wire to complete the circuit, he glanced down at the table and noticed the compass needle deflect:

Instead of remaining parallel to the wire or pointing strictly north, the compass needle swung toward a direction perpendicular to the current-carrying wire.

When Ørsted reversed the battery terminals, reversing the direction of the electrical current: The compass needle swung in the opposite direction.

Ørsted had discovered one of the deepest truths of physics: an electric current creates a magnetic field.

The magnetic force did not pull straight toward or away from the wire like gravity or static electricity; it circulated around the wire in concentric circular rings, following what physicists now call the Right-Hand Rule: if your thumb points in the direction of conventional electric current, your curled fingers show the circular direction of the magnetic field (B).

Electricity and magnetism were not separate forces. They were two faces of a single unified interaction: Electromagnetism.

---

7. Michael Faraday: The Miracle of Induction (1831)

If an electric current creates a magnetic field, the inverse question was inevitable:

For a decade, physicists tried and failed. They placed powerful iron magnets next to copper wires, wrapped magnets in coils, and stared at galvanometers. Nothing happened. The needles remained dead at zero.

The puzzle was solved by a self-educated bookbinder's apprentice and blacksmith’s son from London: Michael Faraday.

Faraday had no formal university education and was not trained in higher mathematics or infinitesimal calculus—he wrote his notebooks almost entirely in prose, quantitative tables, and geometric diagrams rather than symbolic equations. Yet he possessed one of the most penetrating physical, spatial, and experimental intuitions in scientific history.

Faraday realized what everyone else had missed: a static, unchanging magnetic field induces no current. Electromotive force is created only by changing magnetic flux.

               FARADAY'S ELECTROMAGNETIC INDUCTION APPARATUS (1831)
  
                    Copper Wire Coil                   Galvanometer Needle
                 ┌────────────────────┐                  ┌─────────────┐
                 │ ╭──╮ ╭──╮ ╭──╮ ╭──╮│                  │             │
                 │ │  │ │  │ │  │ │  ││ ═══════════════▶ │     /       │
                 │ ╰──╯ ╰──╯ ╰──╯ ╰──╯│                  │    /        │
                 └────────────────────┘                  └─────────────┘
                            ▲
                            │
               Permanent Bar Magnet
               PLUNGED INTO COIL BY HAND!
               [ N | S ] ──▶

On August 29, 1831, Faraday wrapped two separate coils of insulated copper wire around an iron ring:

1. When he connected the first coil to a battery, the magnetic field grew inside the iron ring.
2. At the exact millisecond the circuit was connected, the galvanometer needle on the second coil twitched and returned to zero!
3. While the battery remained connected and the magnetic field was steady, the needle sat motionless.
4. When Faraday disconnected the battery and the magnetic field collapsed, the needle twitched violently in the opposite direction!

Two months later, Faraday dispensed with the iron ring altogether. He took a hollow cylinder of copper wire, hooked it to a galvanometer, and shoved a cylindrical permanent bar magnet inside the coil by hand:

• Plunging the magnet IN: Current flowed!
• Holding the magnet STILL: Zero current!
• Pulling the magnet OUT: Current flowed in the opposite direction!

Faraday had discovered Electromagnetic Induction:

The induced electromotive force (E) is directly proportional to the rate of change of magnetic flux (Φ_B) over time.

The Birth of the Electric Power Grid

Faraday immediately understood the monumental engineering consequence of his discovery:

You did not need expensive, corrosive chemical batteries to create electricity.

If you attach a copper coil to a spinning waterwheel, a steam engine piston, or a windmill, and spin that coil between the poles of a magnet:

Faraday had invented the electric dynamo (generator).

Every power station on Earth today—from a Hoover Dam hydroelectric turbine to a coal-fired generator, a wind turbine off the North Sea, or a nuclear reactor boiling water into high-pressure steam—is doing nothing more than what Michael Faraday did in his London basement in 1831: spinning a coil of copper wire inside a magnetic field to force electrons through transmission lines.

---

8. Summary: The Unification of Force

Milestone	Investigator	Physical Discovery	Modern Direct Descendant
Triboelectric Static Charge	Thales & Gilbert (~600 BCE / 1600)	Friction separates orbital electrons across dielectric surfaces	Photocopiers, laser printers, industrial electrostatic precipitators
Electrostatic Storage	Musschenbroek (1745)	Dielectric capacitors store energy in concentrated electric fields	Flash photography, DRAM computer memory chips, power smoothing
Atmospheric Electricity	Franklin (1752)	Lightning is a high-voltage electrostatic discharge	Lightning rods, building grounding systems, atmospheric physics
Electrochemical Direct Current	Volta (1800)	Redox chemical reactions drive continuous electron flow	Lithium-ion smartphone batteries, electric vehicle powertrains
Electromagnetic Fields	Ørsted (1820)	Moving electric charges generate concentric magnetic fields	Electromagnets, MRI medical scanners, electric relays
Electromagnetic Induction	Faraday (1831)	Time-varying magnetic flux forces current through conductors	Hydroelectric generators, wind turbines, electric transformers, AC grid

Through this eighty-year cascade of physical experiments, an invisible force that once merely lifted feathers was revealed to be the foundation of matter itself.

In our companion explainers across the Physics Series and Chemistry Series, we explore how physical laws developed into the bedrock of modern engineering:

• How Batteries Convert Chemical Energy into Electrical Energy unpacks the electrochemical half-cell potentials, Nernst thermodynamics, and lithium-ion intercalation that evolved from Volta's 1800 pile.
• How Newton's Laws Govern Motion details how classical mechanics established the mathematical laws of force, momentum, and gravitation.
• How Electromagnetism Unifies Nature traces how Maxwell bound Faraday's and Ampère's experiments into four coupled vector equations that predicted light as a traveling wave.
• How Thermodynamics Dictates the Arrow of Time uncovers why heat and entropy create the irreversible direction of physical processes.
• How Quantum Mechanics Redefined Reality explains the breakdown of classical determinism and the discrete quantization of atomic energy levels.
• How Semiconductors and Transistors Actually Work demonstrates how these quantum band structures enabled solid-state silicon switches that power modern computers.
• How Wi-Fi Actually Works and How Binary and Logic Gates Became Computation follow how these electrons are marshaled into wireless packets and arithmetic pipelines.