Question

Two Polaroids $P_1$ and $P_2$ are placed with their axis perpendicular to each other. Unpolarised light $I_0$ is incident on $P_1$. A third polaroid $P_3$ is kept in between $P_1$ and $P_2$ such that is axis makes an angle 45$^{\circ}$ with that of $P_1$ .The intensity of transmitted light through $P_2$ is : -

• A. $\frac{I_0}{4}$
• B. $\frac{I_0}{8}$
• C. $\frac{I_0}{16}$
• D. $\frac{I_0}{2}$

Answer 1

Answer: (B)

$\frac{I_0}{8}$

Answer 2

$I_{2}=\frac{I_{0}}{2} \cos ^{2} 45^{\circ}$
$=\frac{I_{0}}{2} \times \frac{1}{2}$
$=\frac{I_{0}}{4}$
$I_{3}=\frac{I_{0}}{4} \cos ^{2} 45^{\circ}$
$I_{3}=\frac{I_{0}}{8}$