Faraday's law of induction is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators. The law states that:
"The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit."
Or alternatively:
"The electromotive force (EMF) generated is proportional to the rate of change of the magnetic flux."
August 29, 1831, Michael Faraday, working in his laboratory in London, discovered electromagnetic induction. In essence, he found that a changing magnetic field can induce an electric current in a nearby conductor.
What Faraday Did
Faraday wrapped two coils of insulated wire around opposite sides of an iron ring. When he passed a current through one coil (the “primary”), he noticed a momentary current in the second coil (the “secondary”). This meant the magnetic field created by the first coil could induce electricity in the second — but only when the current was changing (switching on or off).
Soon after, he refined the experiment by moving a magnet through a coil of wire and observed that this motion generated a current. From this, he established Faraday’s Law of Induction, which can be summarized as:
A changing magnetic flux through a loop of wire induces an electromotive force (voltage) in the wire.
Why This Was Revolutionary
Before Faraday, people knew about electricity (static electricity, batteries, simple circuits) and magnetism, but the deep connection between the two wasn’t understood. Faraday’s discovery bridged that gap — showing how electricity and magnetism are fundamentally intertwined.
This gave birth to:
Electric generators (turning motion into electricity — the principle behind power stations).
Transformers (changing voltage levels so electricity can travel long distances efficiently).
Electric motors (the reverse principle: turning electricity into motion).
The modern power grid (without induction, we couldn’t generate or transmit electricity at scale).
Broader Impact
It revolutionized physics and engineering, paving the way for James Clerk Maxwell’s equations, which unified electricity and magnetism into a single framework — electromagnetism.
It made the industrial revolution truly “electrical” in its second phase (late 19th to 20th century).
Today, virtually every home, factory, and digital device is powered through systems that rest on Faraday’s insight.
It’s often said that Faraday gave humanity the science of electricity, while later inventors like Nikola Tesla, Thomas Edison, and George Westinghouse gave it the industry.
Faraday and the Royal Institution
Michael Faraday was a largely self-taught scientist, having begun his career as a bookbinder’s apprentice. By the 1830s, he was working at the Royal Institution in London , doing experiments in chemistry and physics.
After his breakthrough in electromagnetic induction on August 29, 1831, Faraday demonstrated it to his colleagues and eventually to statesmen and patrons who supported scientific research.
The Famous Exchange
When Faraday showed how moving a magnet through a coil could generate electricity, many were impressed but puzzled. They didn’t yet see how this invisible spark could be useful.
According to accounts (possibly apocryphal, but widely retold), William Gladstone, a future British Prime Minister who was then Chancellor of the Exchequer, asked Faraday:
But after all, what use is it?
Faraday is said to have replied:
Why, sir, there is every probability that you will soon be able to tax it.
Why This Matters
This anecdote captures something essential:
Faraday’s foresight — he knew that the utility of fundamental discoveries may not be immediately obvious, but they often transform society later.
The role of basic science — it reminds us why governments and institutions should fund pure research. At the moment of discovery, nobody could have imagined electric lighting, telecommunication, or modern computing. Yet all of them trace back to induction.
So in a way, Faraday’s induction experiment wasn’t just a laboratory curiosity. It was the seed of the entire electrical age — from the lightbulb to the smartphone.
From Faraday to the Power Grid
1831 — Faraday’s Discovery
Faraday demonstrates electromagnetic induction: moving a magnet through a coil produces current.
Pure science at this stage — no machines, no practical use yet.
1832–1860s — Early Experiments
Joseph Henry(U.S.) independently discovers induction around the same time.
Early hand-cranked dynamos are built, but they’re weak.
Electricity is still mostly from batteries.
1867 — The Dynamo
Werner von Siemens improves Faraday’s idea and builds the first practical dynamo (generator).
This is the first machine that could produce usable electricity on an industrial scale.
Marks the birth of electrical engineering as a discipline.
1870s — First Power Applications
Arc lamps (bright street lamps) powered by dynamos light up parts of Paris, London, and New York.
Telegraph networks expand — another offshoot of electromagnetism.
Engineers begin thinking about how to bring electricity into homes and factories.
1879 — Edison and the Lightbulb
Thomas Edison invents a practical incandescent lightbulb.
Launches the idea of an electric utility (power stations + distribution to customers).
In 1882, Edison builds the Pearl Street Station in New York, the first commercial power station.
Edison uses direct current (DC), which works only for short distances.
1880s — The War of Currents
Nikola Tesla develops alternating current (AC) systems, which can be transmitted over long distances using transformers (based on Faraday’s induction).
George Westinghouse backs Tesla, leading to the famous AC vs DC battle with Edison.
AC wins — it’s more efficient and scalable.
1890s — First Grids
The Niagara Falls power plant (1895), designed by Tesla and Westinghouse, becomes the first large-scale hydroelectric station.
Electricity is transmitted miles away to Buffalo, NY — proving AC power works.
Soon, cities worldwide adopt AC systems, creating the first true power grids.
1900s–1950s — Electrification
Electricity spreads into homes, factories, and rural areas.
Appliances (radios, refrigerators, washing machines) emerge.
Power grids become national networks.
Today
Virtually every modern technology — from hospitals to the internet — rests on Faraday’s 1831 principle.
Wind turbines, nuclear plants, coal plants, and even solar inverters all rely on electromagnetic induction to generate or manipulate electricity.
In short:
Faraday (1831) → Siemens (dynamo, 1867) → Edison (DC grid, 1882) → Tesla/Westinghouse (AC grid, 1890s) → global electrification.
See Also
Flux
law of electromagnetic induction
Law of Vibrating Atomolic Substances
Laws
Laws of Electrostatic Induction