An unpolarised light beam of intensity $2 I_{0}$ is passed through a polaroid $P$ and then through a

Question

An unpolarised light beam of intensity $2 I_{0}$ is passed through a polaroid $P$ and then through another polaroid $Q$ which is oriented in such a way that its passing axis makes an angle of $30^{\circ}$ relative to that of $P$. The intensity of the emergent light is\

Professor PC Thomas Classes · Answer

(c) : Consider the diagram shown : Intensity passing from $P$ is $I_{0}$, this will be received by Q.\ Now, intensity passing through $Q$ is\ $I=I_{0} \cos ^{2} \delta=I_{0} \cos ^{2} 30^{\circ}$\ $=I_{0} 	imes\left(\frac{\sqrt{3}}{2}ight)^{2}=\frac{3 I_{0}}{4}$\