Question 158: Waves Optics

Question

Unpolarized light of intensity I passes through an ideal polarizer A. Another identical polarizer B is placed
behind A. The intensity of light beyond B is found to be I/2. Now another identical polarizer C is placed between A and B. The intensity beyond B is now found to be I/8. The angle between polarizer A and C is :

Accepted Answer

As after B intensity of  light does not drops, it means both A and B are alligned in single line means their plane of polarization is same.
Let C makes an angle $$	heta $$ with A then C will make $$	heta $$ with B also, as both A and B are alligned in a single line.
So, after C intensity is = $${{m I} \over 2}$$ cos
2
$$	heta $$  , and , intensity after B = $${{m I} \over 2}$$ cos
2
$$	heta $$ $$ 	imes $$ cos
2
$$	heta $$
According to question,
$${{m I} \over 2}$$ cos
4
$$	heta $$ = $${{m I} \over 8}$$
$$ \Rightarrow $$\,\,\, CO
4
$$	heta $$ = $${{m I} \over 4}$$
$$ \Rightarrow $$$$\,\,\,$$ cos$$	heta $$ = $$ = {1 \over {\sqrt 2 }}$$ = cos45
o
$$	herefore\,\,\,$$ $$	heta $$ = 45
o

Answer

60o

Answer

30o

Answer

45o

Answer

0o

Waves Optics

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