This presentation is on the topic polarization of light one of the topics of 1styear physics.

1. POLARIZATION OF LIGHT
Chapter#09(NATURE OF LIGHT)
Presented by: Kanwal Kataria

2. TOPICS
POLARIZATION
DIFFERENT METHODSTO POLARIZE LIGHT
APPLICATIONS OF POLARIZATION

3. s
TRANSVERSEWAVES
LONGITUDINALWAVES

5. The theory about light given by Christian Huygen
suggested that light has wave nature, further it
was confirmed byYOUNG’S DOUBLE SLIT
EXPERIMENT and diffraction property of light
that light has wave nature. But there was still a
question that what type of waves light are?
1. Transverse or longitudinal?
2. Do they travel like sound waves or water
waves?

6. In 1873, sir James clerk Maxwell proposed
that a light wave is produced by oscillating
charge consists of a periodic variation of
electric field vector accompanied by the
magnetic field at right angle to each other
• These vibrations of electrons are not only in a single
plane but in different planes
• Due to vibration of electron in different planes waves in
different directions are generated.
• The two planes of vibration are vertical and horizontal

7. Planes of vibration
Vertical plane
Electron vibrating in vertical plane
generate waves in vertical direction.
Horizontal plane
Electron vibrating in horizontal plane
generate waves in horizontal direction

8. Now if it becomes possible to make an electron to vibrate in a
single plane then it’s vibration is said to be polarized

9. AS A ROPE ORIENTED IN ONE DIRECTION

10. POLARIZATION
The polarization is a phenomenon in which waves of light or other radiation are
restrictedin direction of vibration andcan vibrate only in one direction.
The wave vibrating in a single plane is calledpolarized wave.
Polarization is the property of transversewaves.
Longitudinal waves cannot be polarizedas the particles of longitudinal wave
vibrate parallel to the propagation of waves.

11. UNPOLARIZED WAVE
The wave which contain all planes of
vibration is called polarized wave.
 Natural or artificial sources of lights
are mostly unpolarized . It means that
their light contains all possible
vibrations, thus light spreads in all
directions .
 Examples: light from a bulb, sunlight,
fluorescent lights, flames etc

12. ELECTRIC FIELD VECTORS OF AN ELECTRON MOVING IN ALL
DIRECTIONS

13. There are several methods to polarize this unpolarized light.
1. Selective absorption
2. Reflection
3. Refraction
4. Scattering

14. SELECTIVE ABSORPTION
 A polarized light can be obtained by using a material which transmits
waves whose electric fields vibrate in a plane parallel to a certain direction
of orientation and absorbs waves whose electric fields vibrate in all other
directions.
The materials used for polarization are mostly Dichroic substances and are
capable of polarize light due to their molecular arrangement, tourmaline
crystal and polaroid are examples of dichroic materials.

15. INTHE EXPERIMENT POLAROID ORTOURMALINE CRYSTAL HASTWO
FUNCTIONS
POLARIZER
When we use polaroid disc
to polarize the light, it is
called polarizer.
ANALYZER
When we use polaroid disc
to test polarized light, it is
called polarizer

16. EXPERIMENT
 Light is passed through polaroid in one
plane parallel to the arrangement of
crystal and perpendicular to the direction
of propagation of wave, and all the other
vibrations are absorbed.
 Then this transmitted light is passed
through analyzer which is placed parallel
to polarizer. It will be observed that light
will pass through analyzer without any
restriction.

17. If, the crystal is rotated at an angle the emergent
ray(light) becomes dimmer.
Ultimately at angle of 90 ° the light will be cut off.
Arrows like this
represent that light
is plane or linearly
polarized.There
are also other types
of polarization:
Circular
polarization
Elliptical
polarization.

18. From the experiment it was known that light is polarized as the
vibrations are restricted in directions. So, finally it can be said that
light waves are transverse in nature.
Give a huge round of applause to scientists

19. NOTE: Plane polarization can be
either vertically or horizontally.

21. POLARIZATION BY REFLECTION
Light reflected from certain surfaces
such as glass, sheets plastics, water
can be observed as plane polarized.
The extent of polarization depends
on the angle of reflection.
Complete polarization can be
observed at polarized angle.
At the polarized angle the reflected
ray and the refracted ray in a
transmitted medium are found to be
right angle to each other.

22. POLARIZATION IN EVERY DAY LIFE

23. NOTE:
 In these all methods light was plane polarized
PLANE POLARIZED LIGHT
Plane polarized light consists of waves in
which the direction of vibration is the same for
all waves.

24. Plane polarized light and not plane polarized
light

25. APPLICATIONS OF POLARIZATION

26. .