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What is a Dynamo?

Michael Anissimov
Michael Anissimov
Michael Anissimov
Michael Anissimov

Dynamo is a word that used to simply mean an electric generator, but today, it refers to a generator that produces direct current (DC) using a commutator, an electrical switch that generates electricity from the force of a rotating rod. Like any other generator, its purpose is to produce electricity from mechanical power. The source of the mechanical power could be a dam, windmill, or a coal or oil-burning power plant, with the latter being most common. Dynamos were quickly replaced by other electrical generators because of the advantages of alternating current (AC), inefficiencies of the commutator, and solid state methods for converting AC into DC power.

One of the simplest and earliest electrical generators, the dynamo first used to generate power for industry. The famous inventor Thomas Edison believed that the future of electricity would be based on DC, but it turned out that his eccentric rival, Nikola Tesla, was correct, and that electricity would be based on AC rather than DC, effectively dooming the dynamo to demonstrations in high school science classes.

Dynamos can be found in hydroelectric dams.
Dynamos can be found in hydroelectric dams.

The dynamo is fundamentally based on Faraday's law of induction, which states, "The induced electromagnetic force or EMF in any closed circuit is equal to the time rate of change of the magnetic flux linking the circuit." Basically, this means a current in a closed circuit can be induced when mechanical force is applied against the magnetic field linking the circuit, as in a generator, or vice versa, as in an engine. The first one that was based on Faraday's law was built in 1832 by the French instrument maker, Hippolyte Pixii.

Inventor Thomas Edison believed that direct current electricity was better than alternating current.
Inventor Thomas Edison believed that direct current electricity was better than alternating current.

This generator led the first steps into the use of electricity in industry. Larger and larger ones were built, linked together in a series. The dynamo was not only the first commercially useful electrical generator, but also one of the first motors, which was discovered by accident. Today, it is mainly remembered as a simple device on which more complex, later electrical devices were based, such as the electric motor, the alternating-current alternator, and the rotary converter.

Michael Anissimov
Michael Anissimov

Michael is a longtime AboutMechanics contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

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Michael Anissimov
Michael Anissimov

Michael is a longtime AboutMechanics contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Learn more...

Discussion Comments

YogaJ

It seems the history of the dynamo is very deep, indeed. This article mentions how the dynamo is mainly considered to be a simple device in today's terms, and is only used as a base for more complex devices.

However I argue this point somewhat because hand cranked dynamos still have potential in powering devices without the use of batteries or other non-sustainable power. Think about the flashlights that you crank or shake by hand. Surely these are dynamos?

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    • Dynamos can be found in hydroelectric dams.
      By: ocwo
      Dynamos can be found in hydroelectric dams.
    • Inventor Thomas Edison believed that direct current electricity was better than alternating current.
      By: nickolae
      Inventor Thomas Edison believed that direct current electricity was better than alternating current.