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Exploring Electrical Technology

Exploring Electrical Technology. Advances in the Age of Electricity: Faraday’s Foundation Telegraph Transformed Communications. Highlights of Faraday’s Career. In 1821, demonstrated electromagnetic (em) energy could be converted into mechanical motion via em rotations experiments

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Exploring Electrical Technology

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  1. Exploring Electrical Technology Advances in the Age of Electricity: Faraday’s Foundation Telegraph Transformed Communications

  2. Highlights of Faraday’s Career • In 1821, demonstrated electromagnetic (em) energy could be converted into mechanical motion via em rotations experiments • In 1829, Davy died • By the end of his life, Davy had become envious of Faraday • Freed Faraday from extra work given him in attempt to swamp and distract him (though result backfired anyway since it simply increase his notoriety)

  3. Highlights of Faraday’s Career • Most productive years • 1831 demonstrated mechanical to electrical energy conversion (em induction) • 1832: identified electricity from various sources • 1833: worked on electrolytic decompositions • Later years • 1836 studied electrostatics: Faraday cage • 1845 related light, electricity and magnetism • 1846-1862 other discoveries

  4. Faraday versus Franklin • Education • Work with books • Number of inventions / areas • Commitment to observation/experiment • Morality and interest in common good • Attitude toward patents • Royal Society Membership • Strength in mathematics

  5. Inventions by Faraday’s Contemporaries • The Telegraph: early forms • 1831 Wheatstone & Fathergill (English) • Created the 1st telegraph machine • Used an arrow that pointed to letters of the alphabet • See picture in L’elletricita, p. 56 for a version presented in England in 1837 • Note • The large battery required (Why?): V=IR • Range of early version limited by resistance of wire, since resistance is proportional to length: R  L

  6. The Telegraph: Early Forms • 1833 Gauss & Weber (Germans) • Built an electric version that operated over a distance of 2 km (1.25 miles) • Impressive considering the limitation of wire resistance • 1835 Joseph Henry (American) • Developed basic principles of his telegraph which Morse put into practical form later • Invented electric relay to carry signal farther See schematic diagram for how relays overcame the resistance problem.

  7. The Telegraph takes off • Samuel Finley Breese Morse • Patented his version (1837) that sent letter codes of dots and dashes • Sent his famous message from Washington to Baltimore (1844) •          /            / •         / •                     /      

  8. The Telegraph improves • Alexander Bain (1846): developed a method of sending messages using punched paper tape – greatly improved the speed of transmission • 1854 Electric telegraph installed between Paris and London (European feat)

  9. The Telegraph extended • Thomson (a.k.a. Lord Kelvin) developed a theory of transmitting electrical signals applied to 1st underwater cables (1855) • 1861 New York & San Francisco connected by a telegraph line (American feat) • 1866 Cyrus West Field layed a telegraph cable across the Atlantic Ocean (joined European & American continents) Where would the telegraph be without good sources of voltage?

  10. Development of Voltage Sources • 1832 Hyppolyte Pixii demonstrated a hand driven “magneto-electric machine” – a generator in which a horseshoe magnet rotated in front of two coils • 1834 Clark produced a commercial electromagnetic generator

  11. Development of Voltage Sources • 1859 Gaston Plante invented the storage battery capable of being recharged • 1867 Zenobe Theophile Gramme built the 1st commercially practical generator for producing AC Even better batteries and generators could not overcome the resistance of a length of wire across the ocean, so how did the cable carry signals across the ocean without the use of relays, underwater anyway?

  12. How Transmission Cables Work • The answer lies in the difference between insulated wire versus insulated cable

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