Two beams, A and B, of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam A has maximum intensity (and beam B has zero intensity), a rotation of polaroid through 300 makes the two beams appear equally bright. If the initial intensities of the two beams are IA and IB respectively, then \frac{I_{A}}{I_{B}}  equals ::

 

  • Option 1)

    3

  • Option 2)

    \frac{3}{2}

  • Option 3)

    1

  • Option 4)

    \frac{1}{3}

 

Answers (1)

As we learnt in

Malus Law -

I= I_{0}\cdot \cos ^{2}\theta

\theta = angle made by E vector with transmission axis.

- wherein

I= Intensity of transmitted light after polarisation .

I_{0}= Intensity of  incident light.

 

 We know that 

I_{A}cos^{2}30^{o}=I_{B}cos^{2}60^{o}

I_{A} \left(\frac{3}{4} \right )=I_{B} \left(\frac{1}{4} \right )

\therefore\ \; \frac{I_{A}}{I_{B}}=\frac{1}{3}

Correct option is 4.

 


Option 1)

3

This is an incorrect option.

Option 2)

\frac{3}{2}

This is an incorrect option.

Option 3)

1

This is an incorrect option.

Option 4)

\frac{1}{3}

This is the correct option.

Most Viewed Questions

Preparation Products

Knockout JEE Main April 2021 (One Month)

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 14000/- ₹ 4999/-
Buy Now
Knockout JEE Main May 2021

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 22999/- ₹ 9999/-
Buy Now
Test Series JEE Main May 2021

Unlimited Chapter Wise Tests, Unlimited Subject Wise Tests, Unlimited Full Mock Tests, Get Personalized Performance Analysis Report,.

₹ 6999/- ₹ 2999/-
Buy Now
Knockout JEE Main May 2022

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Live Classes, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 34999/- ₹ 24999/-
Buy Now
JEE Main Rank Booster 2021

Booster and Kadha Video Lectures, Unlimited Full Mock Test, Adaptive Time Table, 24x7 Doubt Chat Support,.

₹ 13999/- ₹ 6999/-
Buy Now
Boost your Preparation for JEE Main 2021 with Personlized Coaching
 
Exams
Articles
Questions