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Question
Can reflection result in plane polarised light if the light is incident on the interface from the side with higher refractive index?
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Solution
If angle of incidence is equal to Brewster’s angle, the transmitted light is slightly polarised and reflected light is plane polarised.
Polarisation by reflection occurs when the angle of incidence is Brewster's angle.
i.e., `tan i_B = ""^1mu_2 = mu_2/mu_1` where `mu_2 < mu_1`
When the light rays travel in such a medium, the critical angle is
`sin i_C = mu_2/mu_1`, where `mu_2 < mu_1`
As `|tan i_B| > |sin i_C|` for large angles `i_B < i_C`
Thus, the polarisation by reflection occurs definitely.
Important point: Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized. This special angle of incidence is named after the Scottish physicist Sir David Brewster.
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