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 ° relative to that of P . The intensity of the emergent light is

Step-by-step solution

When unpolarized light passes from Polaroid, then it becomes polarised light and intensity becomes half of the original, therefore, I 1 = 2 I 0 2 = I 0 . Given here, θ = 30 ° . Using law of Malus for the second polariser, I = I 0 cos 2 θ We have, intensity of emergent light, I 2 = I 1 cos 2 30 ° = I 0 3 4 = 3 I 0 4