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

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° relative to that of P. The intensity of the emergent light is (A) (I0/4) (B) (I0/2) (C) (3 I0/4) (D) (3 I0/2)

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/d62a489f8cbb77ce94ad4306a80ea94c-.png" /> I1=(1/2)(2 I0)=I0 I2=I1 cos 2 30° =I0 ⋅ (3/4)=(3 I0/4)

Q. 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 $3 0^{\circ}$ relative to that of $P$ . The intensity of the emergent light is

$\frac{I _{0}}{4}$

$\frac{I _{0}}{2}$

$\frac{3 I _{0}}{4}$

$\frac{3 I _{0}}{2}$

$I_{1} = \frac{1}{2} (2 I_{0}) = I_{0}$
$I_{2} = I_{1} cos^{2} 3 0^{\circ}$
$= I_{0} \cdot \frac{3}{4} = \frac{3 I _{0}}{4}$

Q. An unpolarised light beam of intensity 2I0​ 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

4I0​​

2I0​​

43I0​​

23I0​​