1. Magnetism Similar to electric forces Magnetic Poles North and South Poles Historic Designations Like Poles Repel, Unlike Poles Attract Due to alignment of atoms in material
2. Magnetic Fields Similar to electric and gravitational fields Magnetic fields are produced by the MOTION of electric charges
3. Magnetic Fields Revolving electron produces field Spinning electron produces field In most atoms, combination of spins and orbits are in opposite directions The fields cancel each other out Some atoms, they don’t cancel Iron, nickel, cobalt, aluminum
4. Magnetic Domains In iron, for example, field by an atom is so strong it causes neighboring atoms to arrange their spins and orbits to line up These clusters form magnetic domains Domains are randomly oriented in ordinary iron, nickel, etc. Can force them to line up with external field
7. Electromagnetics Place a piece of unmagnetized iron in a coil of wire carrying a current Produce a strong magnetic field in the iron by lining up domains Makes the whole thing a very powerful magnet
8. Magnetic Forces and Charges If a charge isn’t moving, a magnetic field has no effect on the charge Reciprocal kind of idea Moving charges produce magnetic fields Magnetic fields apply a force to a moving charge
19. Electromagnetic Induction Faraday’s Law The induced voltage in a coil is proportional to the number of loops, multiplied by the rate at which the magnetic field changes within those loops. The amount of current depends on the resistance of the wire Changing magnetic field in a loop is key!!
20. Electromagnetic Induction Traffic light control (buried loops) Airport Security Systems Mag strips on credit cards Tape Recorders Computer Hard Drives
25. Transformers The more turns, the more voltage induced Step-up Transformer has more turns in secondary than in primary Step-down Transformer has more turns in primary than in secondar
27. Field Induction An electric field is induced in any region of space in which a magnetic field is changing with time A magnetic field is induced in any region of space in which an electric field is changing with time “Let there be light!!!”
