Consider two polaroids A and B as shown. Unpolarised light is incident on polaroid A . Now, both the polaroids are rotated simultaneously by 180 ° in the same sense of rotation such that at every inst

Question

Consider two polaroids A and B as shown. Unpolarised light is incident on polaroid A . Now, both the polaroids are rotated simultaneously by 180 ° in the same sense of rotation such that at every instant, their pass (transmission) axes always remain parallel to each other. During the rotation, intensity of transmitted light through polaroid B

TestHub · Accepted Answer

Intensity after passing through polaroid $A$ is

$I_{A} = \frac{I_{0}}{2}$

$= \frac{I n t e n s i t y o f u p o l a r i s e d l i g h t}{2}$

Intensity after passing through polaroid $B$ is

$I_{B} = I_{A} \cos^{2} θ$

Here, $θ =$ angle between pass axes of $A$ and $B$ .

Here, pass (transmission) axes always remain parallel to each other i.e. $θ = 0$ .

$∴ I_{B} = I_{A} = \frac{I_{0}}{2} = c o n s t a n t$

Hence, during the rotation, the intensity of transmitted light through polaroid $B$ remains the same.

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