16 - Magnetic Magnetic Properties EMA 4144 Physical...

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agnetic Properties Magnetic Properties EMA 4144 Physical Properties of Ceramics Original slides by Y. Meng, Robert A. Schill, Jr., UN, Las Vegas, im t Pierre School f hysics The niversity of Western ustralia Tim St. Pierre, School of Physics, The University of Western Australia Modified and updated by W. Sigmund
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History of Magnets Early Philosophers - Webster’s World Encyclopedia 1999 00 BC he hinese Book of the Devil Valley Master fers to 300 BC - The Chinese Book of the Devil Valley Master refers to lodestone lining up with the earth's magnetic field. ?? BC - Discovery in the west that the lodestone attracts iron 270 AD - Chinese use compass for locating south 1044 AD - Chinese use compass for navigation 12 th Century - Arab physicist - “We know that the magnet loves the lodestone, but we do not know whether the lodestone also loves the magnet or is attracted to it against its will.”
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LODESTONE Natural magnetic iron ore called magnetite First known magnet. Iron filings are g attached to this stone on oxide (rust) is Iron oxide (rust) is seen on the right of e lodestone the lodestone
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ore Recent Philosophers ebster’s More Recent Philosophers - Webster s World Encyclopedia 1999 1600 William Gilbert Clearly explains that the earth behaves like a magnet in Gilbert’s De Magnete. 1635 Henry Gellibrand Reports that compass north varies from year to year in a given place, in a regular way. gy 1749 John Canton Develops a method for making an artificial magnet. 1819 Hans Oersted Magnetic current affects a compass needle 1821 Michael Faraday Creates the first two electrical motors. 831 Michael Faraday Discovers electromagnetic induction discovered earlier but not 1831 Michael Faraday Discovers electromagnetic induction, discovered earlier but not published by Joseph Henry. 1832 Joseph Henry Discovers transformer effect. 1835 Michael Faraday Discovers self-induction, independently of Joseph Henry. 845 Michael Faraday Discovers the Faraday effect: a magnetic field makes the plane of 1845 Michael Faraday Discovers the Faraday effect: a magnetic field makes the plane of polarized light rotate. 1873 James C. Maxwell Influenced (among other things) by Faraday. 1966 various authors The earth's magnetic field is shown to reverse, swapping north and south poles. p 1981 Blakemore & Frankel Discovery that bacteria have a magnetic sense.
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How is a Magnetic Field Generated? Magnetic Field Generated By moving charge By current (which is a moving charge)
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Orientation of Magnetic Field Right Hand Rule Place thumb of right hand in the direction of current Fingers on right hand curl in the gg direction of the magnetic field
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Electromagnetism The current direction in the graphic is for electron flow
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Direction of Magnetic Force I; Direction of Current at P B; Direction f Magnetic of Magnetic Field at P Direction of Force at Point P
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Right Hand Rule Right Hand Rule for Force at P due to I & B ±± Point straightened fingers on right hand in the direction of e current at point P the current at point P ±± Bend fingers in the direction of magnetic field at point P ±± Thumb on right hand points in direction of force experienced t P at P
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This note was uploaded on 03/04/2010 for the course MSE 4144 taught by Professor Sigmund during the Spring '10 term at University of Florida.

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16 - Magnetic Magnetic Properties EMA 4144 Physical...

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