Unpolarized light of intensity I₀ passes successively through three ideal polaroids whose transmission axes are at 0°, 30° and 75°, respectively, with respect to a fixed reference direction. What is the final transmitted intensity?
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Question

Unpolarized light of intensity I₀ passes successively through three ideal polaroids whose transmission axes are at 0°, 30° and 75°, respectively, with respect to a fixed reference direction. What is the final transmitted intensity?

Options

G1 Physics · Accepted Answer

After the first polarizer, I₁ = I₀ ÷ 2. The angle between the first and second transmission axes is 30°. Therefore, I₂ = I₁ cos²30° = (I₀ ÷ 2)(3 ÷ 4) = 3I₀ ÷ 8. The angle between the second and third axes is 75°−30° = 45°. Hence, I₃ = I₂ cos²45° = (3I₀ ÷ 8)(1 ÷ 2) = 3I₀ ÷ 16. Correct option: B.