KVPY 2020-21 SB SX Exam Previous Papers

Question : 91 of 120

Marks: +1, -0

PART-II : PHYSICS

A camera filled with a polarizer is placed on a mountain, in a manner to record only the reflected image of the sun from the surface of a sea as shown in the figure. If the sun rises at 6.00AM and sets at 6.00PM during the summer, then at what time in the afternoon will the recorded image have the lowest intensity, assuming there are no clouds and intensity of the sun at the sea surface is constant throughout the day? (Refractive index of water = 1.33)

12.32PM
3.32PM
5.00PM
6.00PM

Validate

Solution:

Camera will receive minimum intensity when.
Light will incident at Brewsters's angle .

\∴\tan {i}=\µ=4 \/ 3

\⇒{i}=53°

time taken by sun to go from

{A}

{P}

will be

{12 {hr}}/{180°} \×143°=9.53 {hr}=9 {hr} 32 {min}

.
time

=6 {AM}+9 {hr} 32 \min \⇒ 3: 32 {PM}

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