Polarization of light

In electrodynamics, polarization is the property of electromagnetic wave, such as light , that describes the direction of the transverse Electric field E B k

Linearly polarized light For

x x y y x x y y

Circularly polarized light Right circularly polarized light

y Reference axis Time p/4 wt=0 wt=p/4 wt=p/2 wt=3p/4 x E0 For kz=p/4

Left circularly polarized light

Elliptical polarized light

a

State of Polarization Plane polarized light : P state Right circularly polarized light : R state Left circularly polarized light : L state Elliptically polarized light : E state

Natural Light An ordinary light source consists of a very large number of randomly oriented atomic emitters, which radiates a polarized wavetrain for roughly 10-8 sec.

Degree of polarization Completely polarized Completely unpolarized Partially polarized Degree of polarization

Malus’s law

Unpolarized light

Malus’s law

Polarizers Selective absorption or dichorism Double refraction or birefringes Reflection Scattering

Polarization by scattering

Scattering of polarized light by a molecule

Scattering of unpolarized light by a molecule

Why sky looks blue

Blue Sky Earth A B C

Rayleigh scattering Red Orange Yellow Green Blue Violet 1 2 2.5 3 6 10

Red Sunset D C Dust layer B Earth A

White Sun in Blue Sky

Yellow Sky

Red Sunset