Question

Two polaroids $A$ and $B$ are placed with their polaroid axes $30^o$ to each other as shown in the figure. A plane polarised light passes through the polaroid $A$ and after passing through it, intensity of light becomes $I_0$ . What is the intensity of finally transmitted light, after passing through the polaroid $B$ ?

• A. $0.75I_0$
• B. $0.866I_0$
• C. $0.25I_0$
• D. $0.5I_0$

Answer 1

Answer: (A)

The intensity $I$ of the transmitted light varies directly as the square of the cosine of the angle between the transmission direction of polariser and the analyser.
$I=I_{0}co{s}^2\theta$
Intensity of finally transmitted light after passing through the polaroid B is given by $I=I_{0}co{s}^2\theta$ (Intensity)
$I=I_0\cdot co{s}^{2}30^o$
$I=0.75I_0$
where, $I_0$ is the maximum intensity of transmitted light.