Who discovered that electricity and magnetism were two aspects of the same thing?
Nineteenth-century scientist Michael Faraday made several important discoveries in chemistry, but it was his work with electricity that had the greatest impact. His interest in electricity was sparked by a series of experiments conducted by Danish physicist Hans Christian Oersted. In 1820, Oersted discovered a fascinating relationship between electricity and magnetism. He concluded that an electrical current running through a wire also created a magnetic field around the wire.
Faraday immediately began his own research. Several years later, he designed an experiment that wrapped two insulated wires around a large iron ring. When he sent an electrical current through one of the wires, he detected a current running in the other. The current couldn’t have passed from one wire to the other because of conduction—the insulation surrounding the wires made that impossible. Faraday suspected it had something to do with the magnetic field surrounding the first wire.
Later, Faraday made a coil of wire and placed a magnet inside it. He found that when he moved the magnet back and forth, an electrical current began flowing through the wire. The same thing happened if the magnet remained still and he moved the coil back and forth. Although Faraday wasn’t exactly sure why it was happening, he concluded that the changing magnetic field was causing the current to flow through the wires. He had just discovered electromagnetic induction.
Faraday kept experimenting, and soon he saw that a magnetic field could also have an effect on light. This discovery was the first indication that light is a form of electromagnetic energy.
About 20 years later, James Clerk Maxwell used Faraday’s groundbreaking work to write a series of mathematical equations that clearly explained electromagnetic fields and their effect on matter. Maxwell’s work connected the dots laid down by Faraday concerning light, electricity, and magnetism. In one of science’s greatest moments, Maxwell concluded from his research that light must be a form of electromagnetic energy—a discovery that opened the door to much of the scientific research that would dominate the 20th century.
field: a region in space defined by the strength and direction of a force’s influence
conduction: the transfer of heat or electrical energy through a substance
electromagnetic induction: the creation of an electrical current in a conductive substance when it’s exposed to a changing magnetic field
The electrical current that passed from one insulated wire to the other in Faraday’s experiment happened because of mutual induction. The current running through a wire creates a small, changing magnetic field around the wire. When another wire comes near enough, this changing magnetic field induces a current to flow in the second wire as well.
Nearly all the appliances in your home contain induction motors. An induction motor uses an electrical current to create a circle of changing magnetic fields that cause a rotor to spin.
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