4_MagnetBasics0910 - History of Magnets ► Lodestone Magnetism Always pointed in one direction(North – aligned with Earth’s field

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Unformatted text preview: History of Magnets ► Lodestone Magnetism Always pointed in one direction (North) – aligned with Earth’s field Magnetite (Fe3O4) Magnetite Ch. 36 and 37 Types of Substances ►Magnetic—can can attract some non magnetic. magnetic. ►Ferromagnetic— become magnetic when placed in a magnetic field. magnetic Iron, nickel, cobalt Iron, ►Non magnetic Magnetism ► Two poles North-Seeking North South-Seeking South ► Opposite Opposite poles attract attract ► Like poles repel 1 Compass ► When placed in the Earth’s magnetic field: A bar magnet will align so that its north seeking north pole faces Geographic North. A bar magnet will align itself so that its south seeking pole faces Geographic South. seeking Magnetic Domains ► Clusters Clusters of atoms line up - electrons spin electrons in same direction. in ► Microscopic clusters. ► Difference between regular iron and Difference magnetic iron is alignment of domains. magnetic Magnetic Field Strength vs. Domain Magnetic Spin Direction Spin Magnets ► Because Because magnetism is produced by individual atoms, the two poles cannot be separated (difference from charge). (difference 2 To Make a Magnet ► By Contact Nail to magnet Nail ► By Induction What was induction? What ► By How to Demagnetize a Magnet ► Heat ► Contact ► Hammering Electricity “Electromagnets” ► How How do you think lodestones were magnetized? magnetized? Magnetic Fields Magnetic Fields ► Moves Moves from North to South North ► Strongest at Strongest poles where field lines closest. lines ► Exert force on Exert other magnetic fields (metals/other magnets) magnets) 3 Interaction of Magnetic Fields Motor ► Converts Converts Electrical Energy to Mechanical Electrical Energy Mechanical Energy. ► Consists of a Consists permanent magnet, and an electromagnet (the armature/rotor) (the Opposite Poles Like Poles Transformers Generator ► Electromagnetic Induction Producing current by moving a magnet through a coil of wire. through Produces alternating current (AC) Produces ► Converts Converts Mechanical Energy to Mechanical to Electrical Energy Electrical ► Increase Increase or decrease voltage by electromagnetic induction. electromagnetic ► Electricity carried over Electricity long distances at a high voltage. voltage. ► “Stepped up” at power plant. ► “Stepped down” at house. 4 Transformers ► Power plant = 6000V ► Long distance transmission = 120,000V ► City transmission = 2200V ► Household Circuits = 120V 5 ...
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This note was uploaded on 11/13/2011 for the course PHYS 1111 taught by Professor Plascak during the Fall '08 term at University of Georgia Athens.

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