### NEET Solved Paper 2017 Question 23

##### Question: Two Polaroids $ P _1 $ and $ P _2 $ are placed with their axis perpendicular to each other. Un polarised light $ l _0 $ is incident on $ P _1. $ A third polaroid $ P _3 $ is kept in between $ P _1 $ and $ P _2 $ such that its axis makes an angle $ 45^{o} $ with that of $ P _1. $ The intensity of transmitted light through $ P _2 $ is

#### Options:

A) $ \frac{l _0}{16} $

B) $ \frac{l _0}{2} $

C) $ \frac{l _0}{4} $

D) $ \frac{l _0}{8} $

## Show Answer

#### Answer:

Correct Answer: D

#### Solution:

- $ l _2=\frac{l _0}{2}{{\cos }^{2}}45^{o} $ $ =\frac{l _0}{2}\times \frac{1}{2} $ $ =\frac{l _0}{4} $ $ l _3=\frac{l _0}{4}{{\cos }^{2}}45^{o} $ $ l _3=\frac{l _0}{8} $