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1. Depending on the source of light produced, they are
classified as
1.Coherent sources
2.Incoherent sources
1.Coherent source: The source which emits a light wave with the same frequency, wavelength, and
phase or has a constant phase difference is known as a coherent source.
2.Incoherent source: An incoherent source emits a light wave having a different frequency,
wavelength, and phase.
3.Coherent sources produce waves that have a constant phase difference with the same frequency
and amplitude.
4.For these waves to be coherent, one necessary condition is that both must produce waves of the
same frequency and amplitude throughout time.
5.Now, Initially, when these two sources produce their respective waves, there may be some phase
difference between the waves.
6.The other necessary condition for these sources to be coherent is that this phase difference must
also be constant through time. Meaning, that at whatever instant we observe, the two respective
waves of these sources must have the same phase difference.
7.If any of the above two conditions are not fulfilled by wave sources, they will be called incoherent
sources.
8.LASER light is a very good example of coherent sources.
9.The usual household light bulb is an example of an incoherent source.

2. Coherent source Incoherent source
1) The sources of light wave are said to be coherent
when phase difference between the waves emitted
by the source is constant.
2) Coherent sources can emit highly monochromatic
light.
3) In coherent sources the light waves comes from
the groups of atom and these groups act dependent
on each otherother i.e they are in same step.
4) The light waves originated from the coherent
sources are of single frequency.
Examples: Laser light, Sound waves.
1) The sources of light wave are said to be incoherent
source when phase difference between the waves
emitted by the source is changes randomly.
2) Incoherent sources cannot emit a highly
monochromatic light.
3) In incoherent sources light is emitted by the atoms
in discrete steps.
4) The light waves originates from the incoherent
sources are of different frequency.
Example: Light from the sun, Electric bulb.
Difference between Coherent sources and Incoherent sources:
Coherent sources and incoherent sources both are the light sources or it can be a sound wave sources
depending on their frequency and phase difference. The sources which emits the light of constant phase
and same frequency are called as coherent sources. The sources which emits the light of random
frequency and different phase are called as incoherent sources. When two waves produces the
interference pattern so these waves are originates from coherent source. In coherent sources the atoms
are behaves in a cooperative manner. The difference between the coherent sources and incoherent
sources is as follows.

3. In Physics, light is used in a number of studies concerning primarily optics. Light is an electromagnetic wave.
These waves are characterized by their frequencies and wavelengths which determine their properties. Light
is produced from some or the other source for use in studies. The light used in studies can be of two types
depending upon the source used. It can be either coherent or incoherent. Incoherent sources of light are light
sources which produce light waves having different frequencies.
Read on to learn more about its importance, examples and comparison with coherent sources in
this Physics article.
Incoherent Sources
Incoherent sources of light are defined as the sources which produce light waves having a different
frequency, wavelength and phase. The sources which produce incoherent light have no control over when
the atom will undergo a transition in energy level. Thus, different atoms undergo energy transitions at
different times resulting in different phases of the light waves. This also results in different frequencies of the
light waves produced.
The above image shows the different waves of light produced by an
incoherent source of light. In such light, the different light waves interfere
with each other. Truly, however, there is no source which has fully
coherent or incoherent light. All sources either have a higher or lower
range of the same or different types of individual light waves.
Incoherent Sources Examples
The examples of incoherent sources of light are as follows:
•Tungsten filament lamp
•Incandescent lamp
•Light from double slit experiment

4. Incoherent Light Source Coherent Light Source
Light waves produced by
incoherent sources do not have
uniform frequency or
wavelength.
The individual light waves
produced by coherent sources
have the same frequency or
wavelength.
There is no control over the
individual atomic energy
transitions in such sources.
The atomic transitions in such
sources are almost uniform.
Light produced by such sources
is polychromatic and undergoes
interference between individual
sources.
Light produced by such sources
is mostly monochromatic and
does not
undergo interference between
individual sources.
Difference Between Incoherent and Coherent Source
of light

6. What are Radio Frequency bands and its
uses?

7. Polarization of Light Definition
Polarization is a phenomenon induced by the wave nature of electromagnetic radiation, according to physics.
Sunlight is an example of an electromagnetic wave since it travels through the vacuum to reach the Earth.
Because an electric field interacts with a magnetic field, these waves are known as electromagnetic waves.
Polarization is the process of converting non-polarized light into polarized light. The light in which particles
vibrate in all various planes is known as unpolarized light.
Polarized Light and Unpolarized Light
Polarized light and unpolarized light are two types of light that differ in the orientation of their electric field
vibrations.
Polarized Light
Polarized light, on the other hand, refers to light in which the electric field vectors vibrate in a specific plane or
direction. In polarized light, the electric field oscillations occur in a well-defined direction, rather than
randomly. The process of transforming unpolarized light into polarized light is called polarization. Polarization
can occur through various methods, such as reflection, transmission, scattering, or filtering.
Unpolarized Light
The light wave in which the electric field vectors vibrate in all possible directions perpendicular to the
direction of propagation of the light is called unpolarized light. That is unpolarized light electric field vibrated
randomly in all possible planes. We can define unpolarized light as a combination of light waves with all
possible orientations of the electric field vectors. Sources of light such as the Sun or Incandescent bulbs emit
unpolarized light.

8. Polarization of Light
Sunlight and almost every other quite natural and artificial illumination produce light waves whose field vectors
vibrate altogether planes that are perpendicular with reference to the direction of propagation. If the electrical
field vectors are restricted to at least one plane by filtration of the beam with specialized materials, then the
sunshine is mentioned as a plane or linearly polarized with regard to the direction of propagation, and each one
wave vibrating during one plane are termed plane parallel or plane-polarized.