Rami Arieli: "The
Laser Adventure" Chapter 1.1 page 5
Examples for elecromagnetic waves
are:
-
Radio-waves which
have wavelength of the order of meters, so they need big antenas (The dimensions
of an antena are of the same order of magnitude as the wave).
-
Microwaves
which have wavelength of the order of centimeters. As
an example: in a microwave oven, these wavelengths
can not be transmitted through the protecting metal grid in the door, while
the visible spectrum which have much
shorter wavelength allow us to see what is cooking inside the microwave
oven through the protecting grid.
-
x-Rays
which are used in medicine for
taking pictures of the bone structure inside the body.
-
Gamma Rays
which are so energetic, that they cause ionization, and are classified
as ionizing radiation.
The theoretical analysis of electromagnetic waves was the work of James
Clerk Maxwell (1831-1879), and it is summarized in 4
equations (which are beyond our scope) bearing his name.
The discrete aspects of electromagnetic radiation is the result
of Einstein's work at the beginning of the 20th century.