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The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at 22.5° from the polarization axis of one of the polaroids, is (I₀ is the intensity of polarised light after passing through the first polaroid):

Asked in NEET 2025 · Malus's law and polaroids

• (1) (I₀)/2
• (2) (I₀)/4
• (3) (I₀)/8
• (4) (I₀)/(16)

Step-by-step solution

Why the other options are wrong

• (1) Comes from one Malus factor, cos²45°, as if only one polaroid followed the first.
• (2) Uses 45° for the middle sheet, where the transmission is largest: cos²45°sin²45°=1/4.
• (4) Halves I₀ first, as if it were unpolarised; I₀ is already the polarised intensity.

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