Polarization by reflection and refraction
- When an unpolarized beam of light falls on boundary, reflected wave and refracted wave are partially polarized.
- An incident wave is an unpolarized light .Some of the rays will get reflected and some gets refracted.
- Most of the light waves that reflected were polarized waves, which were parallel to the plane.
- Most of the rays along the refracted ray were unpolarized waves with one or two polarized components.
- Refracted Ray à More unpolarized and Reflected rayà more polarized.
- If the angle of incidence varies more and more unpolarized light was able to pass through the surface.
- At one particular value of angle of incidence there was maximumpolarization in the reflected ray.
- Above and below the value of angle of incidence, both reflected and refracted rays were partially polarized.
Brewster’s law:- Brewster’s law states that at any particular angle of incidence, reflected ray is completely polarized; and the angle between reflected and refracted ray is 900.
- At i = iB; where iB = Brewster’s angle of incidence.
- From Snell’s law :- (sin i/sin r)= μ
- => sin iB /(sin (π/2 -iB))
- =>(sin iB /cos iB)=μ
- tan iB = μ
What is the Brewster angle for air to glass transition? (Refractive index of glass = 1.5.)
Refractive index of glass,μ=1.5
Brewster angle = θ
Brewster angle is related to refractive index as:
tan θ =μ
θ =tan-1(1.5) =56.310
Therefore, the Brewster angle for air to glass transition is 56.31°.