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10. Wave optics — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics10. Wave optics1 Mark
MCQ
$n$ polarizing sheets are arranged such that each makes an angle $45^{\circ}$ with the proceeding sheet. An unpolarized light of intensity $I$ is incident into this arrangement. The output intensity is found to be $\frac{I}{64}$. The value of $n$ will be:
  • A
    $3$
  • ✓
    $6$
  • C
    $5$
  • D
    $4$
✓

Answer

Correct option: B.
$6$
b
After passing through first sheet

$I_1=\frac{I}{2}$

After passing through second sheet

$I_2=I_1 \cos ^2\left(45^{\circ}\right)=\frac{I}{4}$

After passing through $n^{\text {th }}$ sheet

$I_{ n }=\frac{I}{2^{ n }}=\frac{I}{64}$

$n=6$

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