2. Electromagnetic waves
•a form of energy waves that have
both an electric and magnetic
field they can also travel in a
vacuum
3. Examples of Electromagnetic Waves
• include radio waves, microwaves,
infrared, visible light, ultraviolet, x-
rays, and gamma rays.
• Radio waves have the lowest energy
and frequency and the longest
wavelength.
4. What is Light?
•Light is a transverse, electromagnetic
wave that can be seen by the typical
human.
•In physics, a transverse wave is a moving
wave whose oscillations are perpendicular
to the direction of the wave.
•the speed of light = 299 792 458 m / s
5. Visible Light Spectrum
• the section of the electromagnetic radiation spectrum
that is visible to the human eye. Essentially, that
equates to the colors the human eye can see.
• It ranges in wavelength from approximately 400
nanometers (4 x 10 -7 m, which is violet) to 700 nm
(7 x 10-7 m, which is red). It is also known as the
optical spectrum of light or the spectrum of white
light
6. • The wavelength of light, which is related
to frequency and energy, determines the
perceived color in the environment.
• Colors near the red color has
lower frequency but higher
wavelength.
• Colors near the violet color
has higher frequency but
lower wavelengths.
7. Types of Light Sources
There are countless sources of light but
they can all be categorized under either of
the two following categories:
•Natural sources
•Artificial sources
8. Natural Sources
The universe is filled with objects that emit light.
Some of the light from these sources reach the earth.
The following things in nature have the ability to
emit light:
SUN
• the major source of light for the earth. The sun is a
massive ball of fire, at the center of which nuclear
fusion produces massive energy. It is the star at the
center of the Solar System. It is a nearly perfect
sphere of hot plasma, with internal convective
motion that generates a magnetic field via a
dynamic process. It is by far the most important
source of energy for life on Earth.
9. Natural Sources
MOON
•provides light as well
but it cannot produce
light on its own. The
light that we get from
the moon is the light
reflected by it from the
sun.
10. Natural Sources
BIOLUMINESCENCE
• some living organisms have the ability
to produce light too. It is called
bioluminescence. It is the effect of
certain chemical reactions within the
organism. Fireflies, jellyfish, glow
worm, certain deep sea plants and
microorganisms can be cited as
examples.
11. Artificial Sources
There are several different types of artificial
light sources, some of these sources are:
INCANDESCENT BULBS
• incandescent lamp or incandescent light
globe is an electric light with a wire
filament heated to such a high temperature
that it glows with visible light.
12. Artificial Sources
HALOGEN LAMPS
• also known as a tungsten halogen,
quartz-halogen or quartz iodine lamp,
is an incandescent lamp consisting of
a tungsten filament sealed into a
compact transparent envelope that is
filled with a mixture of an inert gas
and a small amount of a halogen such
as iodine or bromine.
13. Artificial Sources
COMPACT FLUORESCENT LAMP
• also called compact fluorescent
light, energy-saving light, and
compact fluorescent tube, is a
fluorescent lamp designed to
replace an incandescent light bulb;
some types fit into light fixtures
designed for incandescent bulbs.
14. Artificial Sources
LIGHT-EMITTING DIODE (LED)
• a semiconductor light source
that emits light when current
flows through it. Electrons in
the semiconductor recombine
with electron holes, releasing
energy in the form of photons.
15. CONCLUSION
Light is one of the most important aspects of
human life guiding us both literally and
figuratively we should continue on studying
to further improve technologies that will
make our overall life and future even better.
