Question 213: Waves Optics

Question

As shown in the figure, three identical polaroids P$$_1$$, P$$_2$$ and P$$_3$$ are placed one after another. The pass axis of P$$_2$$ and P$$_3$$ are inclined at angle of 60$$^\circ$$ and 90$$^\circ$$ with respect to axis of P$$_1$$. The source S has an intensity of 256 $$\frac{W}{m^2}$$. The intensity of light at point O is ____________ $$\frac{W}{m^2}$$.

Accepted Answer

By first polaroid P1 intensity will be halved then P2 and P3 will make intensity $\cos ^{2}\left(60^{\circ}ight)$ and $\cos ^{2}\left(30^{\circ}ight)$ times respectively.
Intensity out $=\frac{256}{2} 	imes \frac{1}{4} 	imes\left(\frac{\sqrt{3}}{2}ight)^{2}=\frac{256 	imes 3}{2 	imes 4 	imes 4}=\mathbf{2 4}$

Waves Optics

Choose the correct answer: