1.What's a Magnet? 2.Types of Magnets
3.Electricity and Magnetism? 4.Magnetic Field Lines
5.Current-Induced Fields 6.Solenoids
7.The Earth's Magnetic Field
Intro to Magnetism: Classification of Materials
Types of Materials Examples Characteristics
Nonmagnetic sulfur,copper,diamond,zinc, aluminum domains do not form; although electron spins create magnetic fields, they cancel out.
Ferromagnetic iron(Fe),cobalt(Co,nickel(Ni),neodymium(Nd), samarium(Sm) domains form as electron spin are aligned, but the domains themselves are scrambled until they're placed in a magnetic field.
Permanent Magnets lodestone,compass needle,horseshoe magnet, the earth's core domains are locked into place by impurities
Types of Permanent magnets Composition

(ferromagnetic elements in bold)

Characteristics Relative Strength+ Permanence=Energy Product


lodestone magnetite = iron oxide(Fe3O4) tough to demagnetize but relatively weak


alnico iron + aluminum+ nickel +cobalt developed prior to WWII and played an important role in development of radar and eventually microwave ovens


ferrrites iron oxide, barium and strontium soft and cheap to produce; 75% of magnets on market 0.6 --> 3.6
neo magnets iron + neodymium + boron allow for compact designs of speakers and motors 35-41
sources: Livinggton, James D. The Force is With Us. Britannica Science Annual. 1999