page_title: Electrification
section_title: Development of magnetos, dynamos and generators
hierarchical_section_title: Electrification / History of electrification / Development of magnetos, dynamos and generators
caption_attribution_description: English: Drawing of Faraday disk, the first electromagnetic generator, invented by British scientist Michael Faraday in 1831. The copper disk (D) rotated between the poles of a horseshoe shaped magnet (A), creating a potential difference between the axis and rim due to Faraday's law of induction. If an electrical circuit such as a galvanometer was connected between the binding posts (B) and (B') the motion induced a radial flow of current in the disk, from the axle toward the edge. The current flows into the spring contact (m) sliding along the edge of the disk, out of binding post (B') through the external circuit to binding post (B) , and back into the disk through the axle. Turning it in the opposite direction reverses the direction of current. The caption also says that passing a current from a Bunsen cell (battery) through it would cause the disk to turn, making it function as an electric motor. The labeled parts are given in the caption as: (A) inducing magnet (D) induced disk (B) binding-screw for current entering or exiting axis of disk (B') binding-screw for current entering or exiting circumference of disk (m) rubber (sliding spring contact) for edge of disk. The caption describes it as 'Foucault's and Le Roux's apparatus' so this picture was not drawn from Faraday's original machine, but one owned by Faraday's contemporary French physicist Léon Foucault. The Faraday disk was an inefficient generator because counter-currents flowed back through regions of the disk outside the magnetic field. It was the first homopolar generator Alterations to image: cropped out caption and list of parts.
context_page_description: Electrification is the process of powering by electricity and, in many contexts, the introduction of such power by changing over from an earlier power source. The broad meaning of the term, such as in the history of technology, economic history, and economic development, usually applies to a region or national economy. Broadly speaking, electrification was the build-out of the electricity generation and electric power distribution systems that occurred in Britain, the United States, and other now-developed countries from the mid-1880s until around 1950 and is still in progress in rural areas in some developing countries. This included the transition in manufacturing from line shaft and belt drive using steam engines and water power to electric motors.
  The electrification of particular sectors of the economy is called by terms such as factory electrification, household electrification, rural electrification or railway electrification.
context_section_description: In the years of 1831–1832, Michael Faraday discovered the operating principle of electromagnetic generators.  The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor that is subjected to a varying magnetic flux, as for example,  a wire moving through a magnetic field.  He also built the first electromagnetic generator, called the Faraday disk, a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet.  It produced a small DC voltage.
  Around 1832, Hippolyte Pixii improved the magneto by using a wire wound horseshoe, with the extra coils of conductor generating more current, but it was AC. André-Marie Ampère suggested a means of converting current from Pixii's magneto to DC using a rocking switch. Later segmented commutators were used to produce direct current.
  William Fothergill Cooke and Charles Wheatstone developed a telegraph around 1838-40. In 1840 Wheatstone was using a magneto that he developed to power the telegraph. Wheatstone and Cooke made an important improvement in electrical generation by using a battery-powered electromagnet in place of a permanent magnet, which they patented in 1845. The self-excited magnetic field dynamo did away with the battery to power electromagnets. This type of dynamo was made by several people in 1866.
  The first practical generator, the Gramme machine was made by Z.T Gramme, who sold many of these machines in the 1870s. British engineer R. E. B. Crompton improved the generator to allow better air cooling and made other mechanical improvements. Compound winding, which gave more stable voltage with load, improved operating characteristics of generators.
  The improvements in electrical generation technology increased the efficiency and reliability greatly in the 19th century. The first magnetos only converted a few percent of mechanical energy to electricity. By the end of the 19th century the highest efficiencies were over 90%.
caption: Faraday disk, the first electric generator. The horseshoe-shaped magnet (A) created a magnetic field through the disk (D). When the disk was turned, this induced an electric current radially outward from the center toward the rim.  The current flowed out through the sliding spring contact m, through the external circuit, and back into the center of the disk through the axle.
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