Magnetic effects - wykład

Magnetic e ff ects The magnetic effects are caused mainly by the spin of the electrons of which the matter is
composed, sometimes by the orbital motion of the electrons in the atoms, and sometimes
by the spin or motion of the other particles. The fields are however always describable by
giving a magnetic medium a density per unit volume of magnetic dipole moment which
we call M and which gives rise to magnetic fields in the same way as P gives rise to
electric fields. Thus the first and fourth Maxwell's equations are modified to
∇ ·H = 0−∇·M (4.18)
∇ × E = −
∂(μ0 H)
∂t −
∂(μ0M)
∂t
. (4.19)
Introducing the vector
magnetic Flux Density B = μ0(H+M) (4.20)
the above equations can be written in the more compact form
∇ · B = 0 (4.21)
∇ × E = −
∂B
∂t
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