Depending on where it originates from, the
sun, the moon, lightning, certain types of glowing insects, worms and fishes
etc. are all example of natural sources of light. While, a candle flame,
various types of torches, lamps and light fixtures are amongst the artificial
light sources.
·
Visible
light
Our sun emits light. Really strong intense
light or radiation called electromagnetic radiation or EMR. The radiation is
called electromagnetic because it contains both electric and magnetic
properties. Electromagnetic radiation is a large family consisting seven
members known as The Electromagnetic Spectrum. Our particular family member
which lies in the middle of the spectrums, falls on the earth and which our
eyes detect is called visible light or the visible spectrum. Its fraction is so
small that if we consider the entire EM spectrum to be around 2500 miles, the
visible fraction would be just one inch! It is within this inch that we live in
our world of natural and extra ordinarily high definition color. We enjoy this
privilege of color due to the presence of certain specialized cells in our eyes
called Rods and Cons.
·
Invisible
light
Now
the other type of electromagnetic radiations is also called light but not
visible light. So, automatically they are considered by us to be invisible. So,
now we know the light which we have naturally been introduced to since birth
and that we see throughout our life is actually radiation and radiation of a
good type that an important source of energy for life on earth as we have seen
earlier. Now, just as members of a family differ from one another and have
their own unique identity, so also these fractions of radiation, although part
of the same family of light, are slightly different from one another. These
different are due to three factors that are independent and give each member,
its individuality. These factors are Wavelength, Frequency and Energy. The
shorter the wavelength is the higher the frequencies and energies are. And the
longer the wavelength is the lower the frequency and energy is.
Types of light:
1.
Radio wave: It has the
longest wavelength with lowest frequency and energy. They are used for
broadcasting TV and radio signals because they can cover a greater distance
through the atmosphere due to their large wavelength. They are usually emitted
and received by antennas.
2.
Microwaves: It has
shorter wavelength than radio waves and higher frequencies and energy. These
waves are used in the appliances like the microwave oven. They are also used in
channels of telecommunication like mobile networks, Bluetooth and wireless LAN
protocols.
3.
Infrared: This
region of spectrum is more known for the aspect of heat associated with it as
they have higher energy as compared to radio waves and microwaves. They are
used by appliances like grills and electric stoves for heating and cooking
food. IR is also used as a part of heat therapy to relieve aches and pains.
4.
Visible: Visible
light has the wavelength in the range of 380-780 nanometers. Visible ray are
simply of those wavelengths which our eyes can detect. It has colors and that
is what we see.
5.
UV or Ultra-Violate: The uses
of ultra violate radiations are also widespread in various aspects of life.
They are used as sterilizing agents by the medical industry and by water
purifiers to get rid of harmful bacteria.
It is used by dentist to harden teeth filling and by banks to detect
fake currency notes.
6.
X-Ray: As we are
aware, x-ray is also used to a great extent by the medical industry to examine
the state of bones or foreign object in the body. It is also used by airport
security to scan luggage for partially dangerous objects.
7.
Gamma: Gamma rays
are a type of radiation with the lowest wavelength and the highest energy. They
are the exact opposite of radio waves. They are emitted by radioactive
materials, given off during nuclear explosions and during certain types of
thunder storm. But despite of the fearful reputation they are used to kill
cancer cells for medical and security scanning and also by space observatories
for astronomical observations.
|
Light
|
Wavelength
|
|
Radio wave
|
5m- 1m
|
|
Microwave
|
1 m-1 mm
|
|
Infrared
|
1 mm-780nm
|
|
Visible
|
780nm-380nm
|
|
Ultra Violate
|
380nm-10nm
|
|
X-Ray
|
10nm-0.01 nm
|
|
Gamma Ray
|
0.01 nm-0.00005nm
|
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