JEE Mains · Physics · STD 12 - 10. Wave optics

Two polaroide \(A\) and \(B\) are placed in such a way that the pass-axis of polaroids are perpendicular to each other. Now, another polaroid \(C\) is placed between \(A\) and \(B\) bisecting angle between them. If intensity of unpolarised light is \(I _0\) then intensity of transmitted light after passing through polaroid \(B\) will be :

A \(\frac{I_0}{4}\)
B \(\frac{I_0}{2}\)
C \(\frac{I_0}{8}\)
D \(Zero\)

Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{I_0}{8}\)

Step-by-step Solution

Detailed explanation

\(I _{ A }=\frac{ I _{ o }}{2}\) \(I_C =\frac{ I _{\circ}}{2} \cos ^2 45=\frac{ I _{\circ}}{4}\) \(I _{ B }= I _{ C } \cos ^2 45=\frac{ I _{\circ}}{8}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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