Question

Two polaroids are crossed. lfnow one of them is rotated through 30$^{\circ}$ and unpolarised light of intensity $I_0$ is incident on the first polaroid, then the intensity of transmitted light will be

• A. $\frac{I_0}{4}$
• B. $\frac{3I_0}{4}$
• C. $\frac{3I_0}{8}$
• D. $\frac{I_0}{8}$

Answer 1

Answer: (D)

Intensity through first polaroid, $I_{1}=\frac{I_{0}}{2}$
$\therefore $ Intensity of transmitted light, $I=I_{1}cos^{2}\theta $
$=\frac{I_{0}}{2}\left(cos\right)^{2}\left(\right.\left(90\right)^{o}-\left(30\right)^{o}\left.\right)$
$=\frac{I_{0}}{2}cos^{2}60^{o}$
$=\frac{I_{0}}{8}$