Polarization

POLARIZATION
TOPICS  POLARIZATION OF ELECTROMAGNETIC WAVES  POLARIZING SHEETS

 POLARIZATION BY REFLECTION
 DOUBLE REFRACTION  CIRCULAR POLARIZATION

 POLARIZATION BY SCATTERING
Text Book: PHYSICS VOL 2 by Halliday, Resnick and Krane (5th Edition)
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POLARIZATION OF ELECTROMAGNETIC WAVES

• By convention, we define the direction of polarization of the wave to be the direction of the electric vector. • The plane determined by electric vector and direction of propagation of wave is called plane of polarization (xy plane in figure)

Plane electromagnetic wave

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POLARIZATION OF ELECTROMAGNETIC WAVES

Example: Polarized Microwaves
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POLARIZATION OF ELECTROMAGNETIC WAVES
(a)Representation of a linearly polarized wave with the electric field vibrating in the vertical direction viewed from along the direction of propagation. (b)Representation of an unpolarized wave viewed along the direction of propagation (perpendicular to the page). The transverse electric field can vibrate in any direction in the plane of the page with equal probability. (c)An equivalent representation of the unpolarized wave, as two waves linearly polarized at right angles to one another and with a random phase difference between them. MIT-MANIPAL BE-PHYSICS-POLARIZATION-2011-12 4

POLARIZING SHEETS
Polaroid  Polarizing material The polarizing direction is established during the manufacturing process.
If E is the magnitude of electric vector, only E cos  (y component) passes through the polaroid. Transmitted intensity I = Im cos2  [Law of Malus] where Im  maximum intensity (ie  = 0 or 180 degree)
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POLARIZING SHEETS

Two polarizing sheets whose transmission axes make an angle  with each other. Only a fraction of the polarized light incident on the analyzer is transmitted