Material_Responses - glass plastic porcelain mineral oil...

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Material Responses in Electrostatics and Magnetostatics Dr. Christopher S. Baird, UMass Lowell Dielectric Ferroelectric Parallel- electric Diamagnetic Paramagnetic Ferromagnetic Conductor Direction of material response field compared to inducing field opposite parallel opposite parallel perfectly opposite Material's effect on internally applied E or B field E weakened E strengthened B weakened B strengthened E = 0, B = 0 Characterization ε > ε 0 ε < ε 0 μ < μ 0 μ > μ 0 σ → ∞ Material component interacting polarized bound charge regions polarized bound charge regions magnetized bound currents magnetized bound currents free charges and currents Effect on external fields lines near surface partially sucks in E field lines partially pushes out E field lines partially pushes out B field lines partially sucks in B field lines E is normal B is tangential Force on external charges or magnets attracts charges repels charges repels magnets attracts magnets attracts charges, repels magnets Example materials
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Unformatted text preview: glass plastic porcelain mineral oil nitrogen water diamond barium titanate none in electrostatics water diamond graphite bismuth copper iron steel cobalt ferrites nickel silver copper gold aluminum iron steel Note: Ferroelectricity and Ferromagnetism are nonlinear, history-dependent effects, in contrast to all the other responses. However, for the purposes of general conceptualization, they can be classed with dielectricity and paramagnetism respectively. Parallel-electric materials (distinct from paraelectrics) do not exist in electrostatics. In electrodynamics, however, the permittivity can become negative. This is because the charges get out of phase from the driving fields, but this is a time-dependent effect. Most materials simultaneously exhibit electric, magnetic, and conductive effects, even if only in small amounts. -+-+-+-+-+-+...
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This note was uploaded on 02/13/2012 for the course PHYSICS 95.657 taught by Professor Staff during the Fall '11 term at UMass Lowell.

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