Optics
HAVING STUDIED WAVE PHENOMENA generally, let’s take a look at the special case
of electromagnetic waves. EM waves are transverse traveling waves produced by the
oscillations of an electric field and a magnetic field. Because they are not transmitted by
any material medium, as sound waves are through air molecules, EM waves can travel
through the vacuum of space and give us valuable information about the universe beyond
the Earth’s atmosphere. Electromagnetic waves play a great many roles in our lives: we
use EM waves of different wavelengths to microwave our dinner, to transmit radio
signals, and to x-ray for broken bones. Most important, we are only able to see because
our eyes can detect the EM waves that make up the spectrum of visible light.
Optics is the study of visible light, and how light can be manipulated to produce visual
images.
The Electromagnetic Spectrum
Electromagnetic waves travel through a vacuum at the speed of light, m/s.
As we’ll see in the next chapter, this is the fastest speed there is: anything faster resides at
present only in the realm of theoretical speculation. Because the speed of EM waves is
constant, we can calculate a wave’s frequency if we know its wavelength, and vice versa:
Wavelength and frequency are the only qualities that distinguish one kind of EM wave
from another. As a result, we can list all the kinds of EM waves on a one-dimensional
graph called the electromagnetic spectrum.