1 / 12

Exploring Electrical Technology

Exploring Electrical Technology. Mid 19 th Century Developments in the “Age of Electricity”. Preoccupying Questions.

holly-adams
Download Presentation

Exploring Electrical Technology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Exploring Electrical Technology Mid 19th Century Developments in the “Age of Electricity”

  2. Preoccupying Questions • If lightning occupied minds of electrical explorers during the 18th century, one issue that still puzzled the new mid 19th century explorers was how em waves compare to light. • Success with electric telegraph may well have stirred such a search.

  3. On the trail • Kirchhoff • Credited with electric circuit laws that complemented Ohm’s Law (V=IR) • Current law based on conservation of charge • Voltage law based on conservation of energy • In 1857 demonstrated that electric disturbances propagate on highly conductive wire at the speed of light All the current that goes into a node must come out. All the voltage drops around a loop equal zero.

  4. On the trail • James Clerk Maxwell • Brilliant theorist • Developed a coherent mathematical treatment of electromagnetism by drawing together the work of others • Faraday: em induction & concept of flux • Gauss: law relating sources to e&m fields • Ampere: law relating current magnetic fields • Maxwell’s own contribution: a prediction

  5. Maxwell’s Written Contribution • 2 Publications • A Dynamical Theory of the EM Field(1864) • Used Faraday’s concept of field as a basis • Introduced Maxwell’s 4 basic equations • Electricity & Magnetism (1873) • Contained basic laws of electromagnetism • Predicted phenomena such as radio waves & light as em waves and described them in great detail

  6. Maxwell’s Unique Contribution • Predicted changes (time variation) in Electric fields will produce Magnetic fields even w/out electric currents A time varying magnetic field generates an electric field (from Faraday’s Law) Either an electric current or a time varying electric field generates a magnetic field A magnetic monopole cannot be isolated like an electric charge; magnetic field line circulate An electric field eminates from electric charge density at a point

  7. Quality of Maxwell’s Contribution • Classic equations most concise, yet coherent treatment of em ever formulated and have stood without major change for over 140 years! • Survived 20th century revolutions of Relativity and Quantum Mechanics • Good to 10-10 cm (100x smaller than the atom) • Provides a powerful symbolic description

  8. Reaction to Maxwell’s Theory • Elegant others of his day did not accept until verified experimentally • Heinrich Hertz (1886) • Found em waves (radio waves) travel at the speed of light • Validated Maxwell’s theory & predictions • If Maxwell illustrated magnificence in mathematical formulation, then Edison showed perseverance of trial and error method led to successful invention; by 1886 Edison was already 39 years old!

  9. Thomas (Alva) Edison • From early years, Edison showed traits that later made him famous as a man • Childhood (born in 1847) • Like other children, was curious • Unlike others, Al constantly asked questions… ones his mother could not begin to answer • Often devised his own experiments • Once sat on a nest of eggs to see if he could hatch them! Biographical notes from Experiencing Electricity & Electronics, by Hazen, 1993.

  10. Edison’s School Experience • At age 7, non-stop questions didn’t earn him respect of his teachers • Behavior punished by schoolmaster with a whipping; he thought Al was “addled” and that would cure him • Parents pulled him out of public school and began to home school • Collected almost 100 chemicals to test every experiment he could

  11. Edison as a Youth • At age 12, prepared for economic world by selling candy, fruit and newspapers to passengers of the Grand Trunk Railway • Started printing and publishing the Weekly Herald from the train • Set up his own chemistry lab in the baggage car, right on the train • Accidentally set baggage car on fire; causing the conductor to “box his ears” and throw him off the train

  12. Edison’s Later Life • He became almost completely deaf; historians disagree on how • From his own perspective, Edison considered his disability a blessing, since he thought it enabled him to shut out the outside world and concentrate on the work of his interest • Next time: his adult work in more detail

More Related