KVPY SX SB Exam 05-Nov-2017 Question Paper

Question : 27 of 120

Marks: +1, -0

Two circularly shaped linear polarisers are placed coaxially. The transmission axis of the first polarizer is at 30° from the vertical while the second one is at 60°, both in the clockwise sense. If an unpolarised beam of light of intensity I = 20 W/m

^{2}

is incident on this pair of polarisers, then the intensities

I_1 \and I_2

transmitted by the first and the second polarisers, respectively, will be close to

$I_1 = 10.0$ W/m $^{2}$ and $I_2 = 7.5$ W/m $^{2}$
$I_1 = 20.0$ W/m $^{2}$ and $I_2 = 15$ W/m $^{2}$
$I_1 = 10.0$ W/m $^{2}$ and $I_2 = 8.6$ W/m $^{2}$
$I_1 = 15.0$ W/m $^{2}$ and $I_2 = 0.0$ W/m $^{2}$

Validate

Solution:

I_0 = 20

W/m

^{2}

I_1 = I_ 0/2=20/2=10

W/m

^{2}

I_2 = I_1 \cos ^2 30º

=10(√3/2)^2=10.3/4

= 7.5 w/m

^{2}

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