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We may describe the behaviour of electric and magnetic fields,
and
through the following differential equations, where
and
are constants,
where the electric displacement is given in terms of the electric
field as
,
is the dielectric
constant, with a vacuum
value of
and
is
the charge density.
The magnetic induction
(often referred to as the magnetic
field) is related to the magnetic field
through
.
is the magnetic permeability with a vacuum value
of
.
Finally, the electric current
is related to the electric
field
through Ohm's law
where
is the electrical conductivity.
We have already seen that (3.3) implies that there are no
sources of magnetic field (no magnetic monopoles) and flux tubes have
a constant strength.
Next: Electrostatics
Up: Electromagnetism
Previous: Introduction
Prof. Alan Hood
2000-11-06