Question 232: Waves Optics

Question

A beam of light of intensity $I_0$ falls on a system of three polaroids which are arranged in succession such that the pass (transmission) axis is turned through $60^{\circ}$ with respect to preceding one. The fraction of the incident light intensity that passes through the system is $\left(\cos 60^{\circ}=\frac{1}{2}\right)$

Accepted Answer

According to Malus' law,
$$ I=I_0 \cos ^2 	heta $$
When beam passed through polaroid 1,
$$ I_1=\frac{I_0}{2} $$
When beam passed through polaroid 2,
$$ \begin{aligned} & I_2=\frac{I_0}{2} \cos ^2 60^{\circ} \ 	herefore &\,\,\, I_2=\frac{I_0}{8} \end{aligned} $$
When beam passed through polaroid 3,
$$ I_3=\frac{I_0}{8} \cos ^2 60^{\circ}=\frac{I_0}{8} 	imes\left(\frac{1}{2}ight)^2=\frac{I_0}{32} $$

Answer

$\frac{1}{8}$

Answer

$\frac{1}{32}$

Answer

$\frac{1}{16}$

Answer

$\frac{1}{2}$

Waves Optics

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