III. Differential form with magnetic and/or polarizable media
Gauss' law for electricity
(49)
(50)
V∙D=ρ
D=ε0E+P
where P denotes the polarization. For free space we have D=ε0 ∙E and for
isotropic linear dielectric D =ε∙E. If a material contains polar molecules, they
will generally be in random orientations when no electric field is applied. An
applied electric field will polarize the material by orienting the dipole moments of
polar molecules. This decreases the effective electric field between the plates
and will increase the capacitance of the parallel plate structure.
Gauss' law for magnetism
(51)
V∙ B = 0
Faraday's law of induction
(52)
V×E=-
Ampere's law
(53)
(54)
V× H = J + —
∂t
B = μo( H + M)
where M denotes the magnetization. For free space we have B = μ0 ∙ H and for
isotropic linear magnetic medium B = μ∙ H. The orbital motion of electrons
29