35. 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 its axis makes an angle 45° with that of $P_1$. The intensity of transmitted light through $P_2$ is ?

35. Two Polaroids P1 and P2 are placed with their axis perpendicular to each other. Unpolarised light I0 is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its axis makes an angle 45° with that of P1. The intensity of transmitted light through P2 is ?

(a) \(0\)

(b) \(\frac{I_0}{8}\)

(c) \(\frac{I_0}{16}\)

(d) \(I_0\)

Answer :  (b) \(\frac{I_0}{8}\)

Malus Law :

\(I = I_0 \cos^2 \theta\)

\(I_1 = \frac{I_0}{2} \cos^2 45^\circ\)

\(= \frac{I_0}{4}\)

\(I_2 = \frac{I_0}{4} \cos^2 45^\circ\)

\(= \frac{I_0}{8}\)