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Question 20252
JEE Physics · Hard

Electromagnetic Waves and Wave Optics: Polaroid — Three Polaroid Problem MCQ

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Polaroid — Three Polaroid ProblemHardQuestion 20252

Question

Unpolarised light (I₀) passes through polariser P₁, then P₂ (at 30° to P₁), then P₃ (at 90° to P₁). Final intensity is:
  1. A
    3I₀/32
    Correct
  2. B
    I₀/16
  3. C
    3I₀/8
  4. D
    I₀/8

Correct answer

3I₀/32

Explanation

After P₁: I₀/2. After P₂ (30°): (I₀/2)cos²30° = (I₀/2)(3/4) = 3I₀/8. After P₃ (at 90° to P₁ = 60° to P₂): (3I₀/8)cos²60° = (3I₀/8)(1/4) = 3I₀/32.

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