Part II
Electromagnetism
Electromagnetism is one of the pillars of modern physics, even though it belongs to
classical physics along with Newtonian mechanics. Maxwell’s equations describe
and interpretalmost all electromagnetic phenomena and are basis equations of
classical physics together with Newton equation. Although after the discovery of
relativistic theory Newton equation needed to be modified, Maxwell’s equations did
not virtually have to be changed. In this part we treat characteristics of electromagnetic waves that are directly derived from Maxwell’s equations.
Electromagnetism becomes connected to quantum mechanics, especially when
we deal with emission and absorption of light. In fact, the experiments performed in
connection with the blackbody radiation led to discovery of light quanta and
establishment of quantum mechanics. These accounts are not only of particular
interest from a historical point of view but also of great importance in understanding
modern physics. To understand the propagation of electromagnetic waves in a
dielectric medium is important from a basic aspect of electromagnetism. Moreover,
it is deeply connected to optical applications including optical devices such as
waveguides and lasers. In light of recent progress of the laser devices, we provide
a tangible example of organic lasers as newly occurring laser devices.
The motion of particles as well as spatial and temporal change in, e.g., electromagnetic fields is very often described in terms of differential equations. We
describe introductory methods of Green’s functions in order to solve those differential equations.