Chapter 6 Magnetostatic Fields in Matter 6.1 Magnetization 6.2 The Field of a Magnetized Object 6.3 The Auxiliary Field 6.4 Linear and Nonlinear Media

6.1 Magnetization Diamagnets, Paramagnets, Ferromagnets Torques and Forces on Magnetic Dipoles Effect of a Magnetic Field on Atomic Orbits Magnetization

6.1.1 Diamagnets, Paramagnets, Ferromagnets Magnetized: a net alignment of magnetic dipoles by an applied magnetic field Ferromagnets retain a substantial magnetization indefinitely after the external field has been removed. E.S. M.S. paramagnetsdiamagnets

6.1.2 Torques and Forces on Magnetic Dipoles

This torque lines the magnetic dipole up parallel to : paramagnetism. In a uniform field, the net force is zero. uniform magnetic dipole moment (2)

In a nonuniform field, net force is not zero (3) force onitself

6.1.3 Effect of a Magnetic Field on Atomic Orbits a classical model -e motion gives a steady-like current no B ( ) in 6.1.2

with ( assume r = constant) B↑ Δv > 0 v↑ antiparallel to diamagnetism [ This is just a model. Quantum is needed, indeed.] 6.1.3

6.1.4 Magnetization spin → paramagnetism orbiting → diamagnetism magnetization

6.2 The Field of a Magnetized Object Bound Currents Physical Interpretation of Bound Currents

6.2.1 Bound Currents for a single dipole

bound volume current 6.2.1(2) bound surface current

Ex (3) uniform

6.2.2 Physical Interpretation of Bound Currents for uniform

for non-uniform nonuniform in for non-uniform in 6.2.2

6.3 The Auxiliary Field Ampere’s Law in Magnetized Materials A Deceptive Parallel

6.3.1 Ampere’s Law in Magnetized Materials Ampere’s Law Auxiliary field

6.3.2 A Deceptive Parallel Ex.2. Copper ( diamagnet ) H(r R) = ? Ampere’s loop uniform distributed

6.4 linear and Nonlinear Media Magnetic Susceptibility and Permeability Ferromagnetism

6.4.1 Magnetic Susceptibility and Permeability in E.S., Polarization electric susceptibility in M.S., magnetization magnetic susceptibility

permeability Permeability of free space 6.4.1(2)

Ex.3. sol (3) N turns per unit length

6.4.2 Ferromagnetism Paramagnetic Ferromagnet no B applied remove no with

6.4.2(2)

Iron is ferromagnetic, but if T>T curie ( 770 。 for iron ) curie point it become a paramagnetic. This is a phase transition (3)