Electricity and Magnetism Before Maxwell
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Electricity and Magnetism Before Maxwell

ByUtsav

For most of human history, electricity was a party trick. Rub amber with fur and it would tug at bits of straw; that was about the extent of anyone’s understanding. By 1873, electricity and magnetism had merged into a single mathematical theory that also explained light itself. The path between those two points runs through a kite in a Philadelphia thunderstorm, a French army officer with an oddly sensitive torsion balance, an Italian count who stacked metal discs into the first battery, and an English bookbinder’s apprentice who had almost no formal mathematics at all. This is the story of how electricity stopped being a curiosity and became a science.

Franklin's kite experiment, 1752
Franklin’s kite experiment, 1752

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Franklin and the Single Fluid

Before the 1740s, the dominant view held that electricity came in two separate, opposing substances. Benjamin Franklin, working from his home in Philadelphia, argued something simpler: there was only one “electrical fire,” and objects became charged not by gaining a foreign substance but by having either too much or too little of this single fluid. An object with an excess he called positively charged; one with a deficit, negatively charged. Crucially, Franklin insisted the fluid was conserved — it moved from one body to another, but the total amount never changed. That idea, the conservation of charge, still holds up in modern physics.

Franklin admitted the terminology was a work in progress, writing to his correspondent Peter Collinson that he doubted he could make his ideas fully intelligible with the language available to him. So he built the language himself. Battery, charge, conductor, condenser, plus, minus, positively, negatively — these are all terms Franklin either coined or fixed into their modern electrical meaning. The vocabulary that every physics student still uses today is largely his.

His single-fluid model was also, in a practical sense, a theory of circuits: when something is charged, current flows from the positive body to the negative one, which is why a car battery — two and a half centuries later — still has a plus and minus terminal stamped on it. Franklin’s kite experiment gets the popular attention, but his real contribution was conceptual: he gave electricity a coherent internal logic for the first time.

Coulomb and the Law of Force

Franklin explained what electric charge was. Charles-Augustin de Coulomb, a French military engineer, worked out how strongly it pushed and pulled. Coulomb had spent eight years posted in Martinique before returning to France with permanently damaged health, and it was back home, investigating a law of electrical repulsion first proposed by the English chemist Joseph Priestley, that he built the instrument that would carry his name into physics: a torsion balance sensitive enough to measure forces far too small to feel by hand.

Between 1785 and 1789, Coulomb published the results. Two charges of the same sign repel, opposite signs attract, and the force between them acts directly along the line connecting them. But the crucial, quantitative discovery was that the force falls off with the square of the distance — double the distance and the force drops to a quarter of its original strength — while it scales directly with the size of each charge. It is the same mathematical shape as Newton’s law of gravity, substituting charge for mass. Coulomb went further and showed that magnetic poles obey an inverse-square law too, a result that would later anchor the mathematical theory of magnetism developed by Siméon-Denis Poisson.

Coulomb’s law did for electricity what Newton’s law of gravitation had done for the planets a century earlier: it turned a qualitative story about attraction and repulsion into an equation you could actually calculate with. The unit of electric charge, the coulomb, now carries his name.

Volta and the First Steady Current

Franklin and Coulomb had described static charge — electricity that built up and then discharged in a spark. What nobody had was a continuous current, a steady flow that could be studied, measured, and put to use. That changed in 1799, when the Italian physicist Alessandro Volta built the voltaic pile.

Volta’s motivation was, in part, an argument. His countryman Luigi Galvani had claimed that dissected frogs’ legs twitched because animal tissue itself generated a mysterious “animal electricity.” Volta suspected the tissue wasn’t the source of the electricity at all — it was just a conductor, reacting to a current generated somewhere else. To prove it, he stacked alternating discs of two different metals separated by cloth soaked in brine, and found that the pile produced a steady current with no animal tissue involved anywhere. It was the first battery, and the first genuinely continuous, reproducible source of electric current in history.

Volta's wet pile, 1800
Volta’s wet pile, 1800

The significance is hard to overstate. A spark from a rubbed amber rod lasts a fraction of a second and tells you almost nothing about the underlying process. A steady current, by contrast, can be traced, measured, and used to run experiments that unfold over minutes or hours. Volta’s pile is the reason electrochemistry, electromagnetism, and eventually electrical engineering became possible as ongoing experimental programs rather than one-off demonstrations. His name lives on in the volt, the unit of electromotive force.

Faraday and the Discovery of Induction

Michael Faraday’s route into science was almost accidental. Apprenticed to a London bookbinder at fourteen, he read the volumes brought in for rebinding rather than simply repairing them, and the entry on electricity in the Encyclopædia Britannica caught him completely. He built a crude electrostatic generator out of old bottles and started experimenting on his own. A ticket to attend chemistry lectures by Humphry Davy at the Royal Institution changed the trajectory of his life; Faraday sent Davy his lecture notes, asked for a job, and eventually became his laboratory assistant.

The discovery that pulled Faraday toward electromagnetism came from elsewhere first: in 1820, the Danish physicist Hans Christian Ørsted found that an electric current flowing through a wire deflects a nearby compass needle — the first solid evidence that electricity and magnetism were connected phenomena rather than separate ones. Faraday, grasping the implications, built an apparatus that converted this circular magnetic force into continuous motion, producing the first electric motor.

But Faraday’s defining discovery came a decade later. On August 29, 1831, he wound insulated wire around one side of an iron ring and connected it to a battery, then wound a separate wire around the other side and connected that one to a galvanometer. When he closed the battery circuit, the galvanometer needle jumped — a current had appeared in a wire that wasn’t even connected to the battery. When he opened the circuit again, the needle jumped the opposite way. A changing magnetic field, he realized, was enough to induce a current in a nearby conductor, even without any direct electrical connection.

He went on to show that moving a permanent magnet in and out of a coil produced the same effect, and that the strength of the induced current depended on how quickly the conductor crossed the magnet’s “lines of force.” That insight led directly to the first dynamo — a spinning copper disc between the poles of a magnet, producing continuous current — and, run in reverse, to the modern electric motor.

Faraday had almost no formal mathematical training, and he thought about electricity and magnetism visually, in terms of lines of force filling the space around a wire or magnet, rather than through equations. That intuition turned out to be more prescient than anyone at the time realized.

The Search for Unification

By the 1820s, three separate strands were visible: Ørsted had shown current could produce magnetism; André-Marie Ampère, working almost immediately after Ørsted’s result reached Paris, showed that two current-carrying wires attract or repel each other depending on the direction of their currents, and worked out a mathematical law — now called Ampère’s law — describing the force between them precisely. He coined the very term “electrodynamics” for this new science, and in 1827 published the treatise that founded it. The third strand was Faraday’s induction: a changing magnetic field could generate current on its own.

What was still missing was a single framework that tied static charge, steady current, magnetism, and induction together as different faces of one underlying phenomenon. That is the task James Clerk Maxwell took up in the 1860s. Maxwell translated Faraday’s picture of lines of force filling space into a rigorous mathematical field theory, and in doing so found something Faraday’s intuition had gestured toward but never proven: that a changing electric field, like a changing magnetic field, could itself generate a field of the other kind. The consequence was a set of equations predicting that these coupled, self-sustaining oscillations would travel through space as a wave — and when Maxwell calculated the speed of that wave from constants measured in ordinary laboratory experiments, it came out equal to the speed of light. Electricity, magnetism, and optics, three subjects that had been studied separately for over a century, turned out to be the same subject.

Maxwell laid this out fully in his 1873 Treatise on Electricity and Magnetism, built on the experimental foundation that Faraday — a man who never wrote a formal equation in his life — had spent decades constructing by hand.

Why It Matters

None of this was inevitable. Franklin could have stuck with the two-fluid theory; Volta might never have doubted Galvani; Faraday could easily have stayed a chemist, which is how he actually started his career. What makes this stretch of the eighteenth and nineteenth centuries remarkable is how a sequence of individually modest results — a torsion balance measurement here, a stack of metal discs there, a needle that twitched the wrong way — accumulated into a unified field theory that didn’t just explain existing phenomena but predicted a new one: electromagnetic radiation, including the visible light we see with every day. Every generator, motor, radio signal, and wireless connection built since then is, in some sense, still running on Maxwell’s synthesis of Franklin’s fluid, Coulomb’s force law, Volta’s current, and Faraday’s lines of force.

Open Questions and Caveats

A few things are worth flagging for accuracy. Franklin’s single-fluid model was an important conceptual leap, but it is not what modern physics uses to describe charge at the level of electrons and protons — it survives mainly as an intuitive picture and in the sign convention we still use. Faraday’s own theoretical concept of an “electrotonic state” in a wire, which he used to make sense of induction, never had solid experimental support and was eventually superseded by Maxwell’s field equations rather than confirmed by them. And while this piece treats Ørsted, Ampère, and Faraday as the immediate run-up to Maxwell, the full mathematical unification also drew on contributions from other nineteenth-century physicists working on electrodynamics that go beyond the scope of a single article.

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  1. Pingback: How James Clerk Maxwell's 4 equations Unified Electricity and Magnetism - Celestial Inquiry

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