A beam of unpolarized light is passed first through a tourmaline crystal A and then through another tourmaline crystal B , oriented so that its principal plane is parallel to that of A. The intensity of the emergent light is I. The crystal A is now rotated by 45∘ in a plane perpendicular to the direction of the incident ray. Find the ratio of the final intensity of the emergent light, in the second case, to that in the first case.

A beam of unpolarized light is passed first through a tourmaline cryst

1.	A beam of unpolarized light is passed first through a tourmaline crystal A and then through another tourmaline crystal B , oriented so that its principal plane is parallel to that of A. The intensity of the emergent light is I. The crystal A is now rotated by 45∘ in a plane perpendicular to the direction of the incident ray. Find the ratio of the final intensity of the emergent light, in the second case, to that in the first case.
Answer» A beam of unpolarized light is passed first through a tourmaline crystal $A$ and then through another tourmaline crystal $B$ , oriented so that its principal plane is parallel to that of $A$ . The intensity of the emergent light is $I$ . The crystal $A$ is now rotated by $45^{\circ}$ in a plane perpendicular to the direction of the incident ray. Find the ratio of the final intensity of the emergent light, in the second case, to that in the first case.