Q30E - University Physics with Modern Physics

Question

The refractive index of a certain glass is 1.66. For what incident angle is light reflected from the surface of this glass completely polarized if the glass is immersed in (a) air and (b) water?

Step-by-Step Solution

Answer

       (a) The incident angle, if the glass is immersed in the air, is $58.9°$

       (b) The incident angle, if the glass is immersed in the water, $51.3°$

Step 1: Brewster’s law

Brewster’s law for polarising angle;

Here, 

The polarising angle is an incidence angle for which all reflected light is polarised, indicating that the electromagnetic wave's electric field has a defined direction.

Step 2: Incident angle if the glass is immersed in air

(a) Medium 1 is air, ${\mathrm{n}}_1=1$

     Medium 2 is glass, ${\mathrm{n}}_2=1.66$

Hence, the incident angle if the glass is immersed in the air is $58.9°$

Step 3: Incident angle if the glass is immersed in water

(b) Medium 1 is water, ${\mathrm{n}}_{!}=1.33$

        Medium 2 is glass, ${\mathrm{n}}_2=1.66$

Hence, the incident angle if the glass is immersed in the water is $51.3°$