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A polaroid (I) is placed infront of a monochromatic source. Another polariod (II) is placed in front of this polaroid (I) and rotated till no light passes. A third polaroid (III) is now placed in between (I) and (II). In this case, will light emerge from (II). Explain.
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When a monochromatic light is placed infront of polaroid
(I) as shown in diagram
According to question, monochromatic light emerging from polaroid (I) is plane polarised. When polaroid (II) is placed infront of this polaroid (I), and rotated till no light passes through polaroid (ii), then (i) and (ii) are set in crossed positions, i.e., pass axes of I and II are at $90^{\circ}$.
From the above figure, where a third polaroid (III) is placed between polaroid (I) and polaroid II.
When a third polaroid (III) is placed in between (I) and (II), no light will emerge from (II), if pass axis of (III) is parallel to pass axis of (I) or (II) (when $\theta=0^{\circ}$ ). In all other cases, light will emerge from (I). as pass axis of(II) will no longer be at $90^{\circ}$ to the pass axis of (III).
(I) as shown in diagram
According to question, monochromatic light emerging from polaroid (I) is plane polarised. When polaroid (II) is placed infront of this polaroid (I), and rotated till no light passes through polaroid (ii), then (i) and (ii) are set in crossed positions, i.e., pass axes of I and II are at $90^{\circ}$.
From the above figure, where a third polaroid (III) is placed between polaroid (I) and polaroid II.
When a third polaroid (III) is placed in between (I) and (II), no light will emerge from (II), if pass axis of (III) is parallel to pass axis of (I) or (II) (when $\theta=0^{\circ}$ ). In all other cases, light will emerge from (I). as pass axis of(II) will no longer be at $90^{\circ}$ to the pass axis of (III).
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