Question

Plane polarised light is incident on a plate of quartz is cut with faces parallel to its optic axis if the phase difference between two rays is 60° calculate the thickness of plate
Given:- refractive index of denser media is 1.5583 A°, the refractive index of rarer media is 1.5422 and
Wavelength = 5000 A°

Answer 1

Answer:

0.00091cm

Explanation:

thickness=[(5000*10^-8)*(60*π/180)] / [2π(1.5583-1.5422)] = 0.00091cm

Answer 2

Given:

phase angle θ = 60°

the refractive index of denser media $\mu_d$ = 1.5583

the refractive index of rarer media $\mu_r$ =  1.5422

Wavelength λ = 5000 A°

To find:

thickness t =?

Explanation:

Here the refractive index of a denser medium is greater than the refractive index of a rarer medium.

Hence $\mu_d$ > $\mu_r$

The thickness of plane-polarized light is given by

$\displaystyle t= \frac{\lambda}{4\ (\mu_d-\mu_r)}$

where

t = thickness of a plate

λ = Wavelength

$\mu_d$ = the refractive index of a denser medium

$\mu_r$ = the refractive index of a rarer medium

Put the given values in the above equation, we get,

$\displaystyle t= \frac{5000}{4(1.5583-1.5422)}$

by solving the above equation, we get

t = 77639 A°

t = 7.7639 μm

∴ The thickness of a plate is 7.7639 μm.