This Day in Tech History

On This Day . . .

One of Einstein’s Heroes


August 29, 1831: Faraday Discovers Electromagnetic Induction

English scientist Michael Faraday discovers electromagnetic induction, the primary principle behind electric motors and generators, inventions that power and drive our electronic technology of today.

Michael Faraday is generally credited with the discovery of induction in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829.

Faraday in his youth

Faraday in his youth

Faraday’s law of induction is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF). It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids.

Faraday appeared in many early photographs, such as this daguerreotype

Faraday appeared in many early photographs, such as this daguerreotype

Although Faraday received little formal education he was one of the most influential scientists in history. It was by his research that Faraday established the basis for the concept of the electromagnetic field in physics.

Faraday also established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena. He similarly discovered the principle of electromagnetic induction, diamagnetism, and the laws of electrolysis.

His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, and it was largely due to his efforts that electricity became practical for use in technology.

Albert Einstein kept a picture of Faraday on his study wall, alongside pictures of Isaac Newton and James Clerk Maxwell. Physicist Ernest Rutherford stated; “When we consider the magnitude and extent of his discoveries and their influence on the progress of science and of industry, there is no honor too great to pay to the memory of Faraday, one of the greatest scientific discoverers of all time”.



For more on the story . . .

In 1821, soon after the Danish physicist and chemist Hans Christian Ørsted discovered the phenomenon of electromagnetism, Davy and British scientist William Hyde Wollaston tried, but failed, to design an electric motor. Faraday, having discussed the problem with the two men, went on to build two devices to produce what he called “electromagnetic rotation”.

Disc Generator

Disc Generator

One of these, now known as the homopolar motor, caused a continuous circular motion that was engendered by the circular magnetic force around a wire that extended into a pool of mercury wherein was placed a magnet; the wire would then rotate around the magnet if supplied with current from a chemical battery. These experiments and inventions formed the foundation of modern electromagnetic technology. In his excitement, Faraday published results without acknowledging his work with either Wollaston or Davy. Needless to say they weren’t very happy about that.

1889 replica of a Faraday Disc Generator

1889 replica of a Faraday Disc Generator

From his initial discovery in 1821, Faraday continued his laboratory work, exploring electromagnetic properties of materials and developing requisite experience.

Drawing of Michael Faraday's experiment demonstrating electromagnetic rotation

Drawing of Michael Faraday’s experiment demonstrating electromagnetic rotation

Faraday’s breakthrough came when he wrapped two insulated coils of wire around an iron ring, and found that, upon passing a current through one coil, a momentary current was induced in the other coil. This phenomenon is now known as mutual induction. The iron ring-coil apparatus is still on display at the Royal Institution.

iron ring-coil apparatus

iron ring-coil apparatus

Faraday would later use the principles he had discovered to construct the electric dynamo, the ancestor of modern power generators and the electric motor.



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