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JEE Main 202126 AugustEvening Shift

Exam: JEE Main
Year: 2021
Date: 26 August
Shift: Evening Shift
Subject: Physics
Chapter: Wave Optics

JEE Main 2021 · 26 August · Evening Shift · Physics · Wave Optics

A source of light is placed in front of a screen. The intensity of...

A source of light is placed in front of a screen. The intensity of light on the screen is

I

. Two Polaroids

{P}_{1}

and

{P}_{2}

are so placed in between the source of light and screen that the intensity of light on the screen is

\dfrac{I}{2}

. Then the

{P}_{2}

, should be rotated by an angle of (degrees) so that the intensity of light on the screen becomes

\dfrac{3I}{8}

.

A source of light is placed in front of a screen. The intensity of light on the screen is I . Two Polaroids P _ 1 and P

Correct answer

30

Step-by-step solution

A source of light is placed in front of a screen. The intensity of light on the screen is I . Two Polaroids P _ 1 and P

Recall the law of Malus ${I}^{'} = \dfrac{I}{2}\cos^{2}\theta$

Here $\theta$ is the angle between two polaroids,

$⇒ \dfrac{3I}{8} = \dfrac{I}{2}\cos^{2}\theta$ $⇒ \theta = 30 °$ .

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