By Robert Hazen, Ph.D., George Mason University
Scientists expect the physical world to display a kind of order, a kind of symmetry. Gravity is symmetrical; energy and mass are conserved in transformations. The same thing should apply to electricity and magnetism. Since moving electricity in a coil of wire produces magnetic effects, scientists had a strong hunch that somehow moving magnets should produce electricity. This was demonstrated conclusively by British physicist Michael Faraday in 1831.
Michael Faraday
Michael Faraday came to science in a strange roundabout way. He was born in 1791 in South London, the third of four children of a blacksmith. The family’s finances were in terrible shape, so to help make ends meet, the young Michael was apprenticed at the age of 13 to a London bookseller, who taught Michael the art of bookbinding.
Faraday learned to bind books quite beautifully. And he began to read avidly, everything he could get his hands on. He was especially fascinated by the Encyclopedia Britannica, especially the articles on science, which he loved. Especially influential was the article on electricity in that early edition which he was binding at the time.
Faraday at Davy’s Lectures
Faraday became enamored with science. He then began attending public lectures, notably by Humphry Davy at the Royal Institution of Great Britain in London. Faraday transcribed the lecture notes from Davy.
He then bound the notes quite beautifully and presented them to Davy as a calling card. Davy was impressed. Unfortunately, at that time there was no position at the Royal Institution, and Faraday was resigned to spending the rest of his life as a tradesman binding books.
Learn more about magnetism and static electricity.
Faraday at the Royal Institution
But, as luck would have it, one of the young assistants in Davy’s laboratory was fired for brawling, and Faraday was hired in 1813 as Davy’s lab assistant. And that really changed the history of science. Faraday served as Humphry Davy’s lab assistant, and he flowered into a distinguished scientist in his own right.
By the 1830s, he had made major contributions in chemistry and physics. He eventually rose to take his mentor’s place as a researcher and as the public lecturer for the Royal Institution.
This is a transcript from the video series The Joy of Science. Watch it now, on Wondrium.
The Quest for Unity
Faraday’s background may have pointed him in the direction of these scientific investigations. He was raised a Sandemanian. This is a Protestant sect that emphasizes the unity of the universe. It’s been suggested that Faraday’s religious background prepared him to look for unity in the different physical phenomena of the natural world.
It was Faraday who demonstrated that the various forms of electricity—that is animal electricity, lightning, the electricity from a battery—are all the same. It’s this kind of unification that Faraday loved, and he looked at electricity and magnetism and wanted to unify those phenomena as well.
Experiment with Coils
Faraday’s most famous experiment took place in 1831, and he incorporated this assumed symmetry of electromagnetism. He attached one coil of wire to a battery, thus creating a magnetic field. Next to this coil, he placed a second coil of wire in a circuit, but there was no battery. Even though the second coil of wire wasn’t attached to any source, an electric current flowed through that second coil of wire just being brought near the first one.
Faraday concluded that the magnetic field produced by the first circuit, the electromagnet, induced a current in the second circuit. This is the phenomenon of electromagnetic induction. The exact same effect occurs when a magnet, when just a normal magnet, is waved or wiggled in the vicinity of a coil of wire.
Transformers
We use devices called transformers in our lives on a daily basis. In a transformer, you put electrical current from the wall outlet through one coil of wire, so electricity flows into this coil of wire, and that produces an electromagnetic field. You then always will see a second coil of wire nearby, and what happens is that as the current flows through the one magnet it induces a current in the second one.
But, in general, that current will be at a different voltage. And so this is a way in household appliances of transferring voltage of one type, for example, 115 volts from your wall circuit, to another kind of voltage. That’s a transformer, a very important electrical device—something that Michael Faraday invented almost 200 years ago.
Learn more about electricity.
Generating Electricity
The demonstration that moving magnets can produce electricity in a coil wire immediately suggested a new procedure for generating electricity in our everyday lives. You place a coil of wire between two magnets. Then you spin that coil of wire, and electricity will be produced. This device is what we call an electric generator, or dynamo.
It’s the centerpiece of every electric power plant. The energy to spin those coils to provide that rotary motion can be provided by water. In a hydroelectric plant, water flowing through a dam turns a water wheel device—that’s where the spinning motion can come from.
It can come from steam in a coal burning power plant, or in a nuclear power plant. It can come from gasoline, in a gasoline engine that turns the coils of wire and, therefore, generates electrical power. But all you have to do is rotate coils of wire against another magnet, and you produce electric charge.
Common Questions about Faraday and Electromagnetic Induction
At the age of 13, Michael Faraday was apprenticed to a bookseller, who taught him the art of bookbinding.
Faraday demonstrated that the various forms of electricity—that is animal electricity, lightning, the electricity from a battery—are all the same.
Faraday attached one coil of wire to a battery, thus creating a magnetic field. Next to this coil he placed a second coil of wire in a circuit, but there was no battery. Even though the second coil of wire wasn’t attached to any source, an electric current flowed through that second coil. Faraday concluded that the magnetic field produced by the first circuit, the electromagnet, induced a current in the second circuit. This is the phenomenon of electromagnetic induction.
