Q29E - University Physics with Modern Physics

Question

A parallel beam of unpolarized light in air is incident at an angle of 54.5° (with respect to the normal) on a plane glass surface. The reflected beam is completely linearly polarized. (a) What is the refractive index of the glass? (b) What is the angle of refraction of the transmitted beam?

Step-by-Step Solution

Answer

(a) The refractive index of the glass is 1.4

 (b) The angle of refraction is $35.5°$

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: Snell’s law

The part of the light that continues into the second medium is transmitted rather than reflected, but the transmitted Ray changes direction as it crosses the boundary. Refraction is the transmission of light from one medium to another with a change in direction. Snell's law describes the angles of incidence and refractive right.

Here;

Step 3: Refractive Index of the glass

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

     Medium${\mathrm{n}}_2$for glass

Hence, the refractive index of the glass is 1.4

Step 4: Angle of refraction of the transmitted beam

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

     Medium ${\mathrm{n}}_2$ for glass, Rl = 1.4

Hence, the angle of refraction is