In
everyday usage, we use the word light to mean only those
forms of radiation that we can see. For our purposes we
will use light to mean all of the frequencies of radiation
shown in the diagram below, known as the electromagnetic
spectrum or EMS.
The
EMS has been broken up into types, consisting of bands of
frequencies, as shown below, gamma rays, x-rays, etc. We
have found uses for many of these types of radiation, examples
of which are given below.
Light
is always in motion and cannot be stored, so it is a potential
type of energy. You might say that light is essentially
"pure" energy, since it theoretically has no mass.
Type
of Radiation
Some
Applications
X-Rays
Taking
x-ray pictures of internal parts of the body. Some parts of
the body allow x-rays to pass while others, like bones, do not.
Visible
Light
Microscopes,
telescopes, lamps, traffic stop lights, flashlights, etc.
Infrared
Night
vision glasses, heat lamps, tanning lamps.
Radar
Detection
of objects such as airplanes, boats, people or the speeds of
cars.
Microwave
Cooking
food.
Radio
Waves
Radio
communications and radio telescopes.
Light is simultaneously
a wave and a particle. The higher the frequency, the more energy
the light or electromagnetic radiation contains. The greater the
frequency, the more energy each particle, called the photon, contains.
