Unpolarized light of intensity I is incident on a system of two polarizers, A followed by B. The intensity of emergent light is I/2. If a third polarizer C is placed between A and B, the intensity of emergent light is reduced to I/3. The angle between the polarizer A and C is $θ .$ Then

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

$\cos θ = {(\frac{1}{3})}^{1 / 4}$

$\cos θ = {(\frac{1}{3})}^{1 / 2}$

$\cos θ = {(\frac{2}{3})}^{1 / 4}$

$\cos θ = {(\frac{2}{3})}^{1 / 2}$

answer is A.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

Case :I
Question Image
As light intensity does not change after passing through polarizer B Axis of B is parallel to axis of A
Case : II

By Malus law have
$I_{C} = \frac{I}{2} \cos^{2} θ$ and $I_{B} = I_{C} \cos^{2} θ = \frac{I}{2} \cos^{4} θ$
Given that $I_{B} = \frac{I}{3}$ $\Rightarrow \frac{I}{3} = \frac{I}{2} \cos^{4} θ$ $\Rightarrow \cos θ = {(\frac{2}{3})}^{1 / 4}$