Chapter 13 - Electric Circuits

Announcements Electrical Resistance Magnetic Fields Final QuestionsA brief history of magnetismabout 4,000 years ago: Legend has it that while herding sheep in an area of Northern Greece calledMagnesia, an elderly shepherd named Magnes found that both the nails in his shoes and the metal tip ofhis staff became firmly stuck to a large, black rock upon which he was standing (magnetite)1269: Pierre de Maricourt describes the poles of a magnet; subsequent experiments reveal that everymagnet has two poles, called north (N) and south (S) which exert forces on other poles1600: William Gilbert suggests that the Earth is a permanent magnet1819: Hans Christian Oersted discovers that an electric current in a wire can deflect a nearby compassneedle (relationship between electricity and magnetism)1831: Michael Faraday and Joseph Henry independently show that a changing magnetic field creates anelectric field (electromagnetic induction)1861: James Clerk Maxwell finds that a changing electric field creates a magnetic field (Maxwell’scorrection)Electric Circuits