1. I₀/2 2. I₀/4 3. I₀/8 4. I₀/16

Answer: 3. I₀/8 Key idea: apply Malus's law, I=I₀cos²θ , at each polaroid. The middle sheet is at 22.5^° to the first, and 90^°-22.5^°=67.5^° to the last (crossed) sheet. I=I₀cos²(22.5^°)cos²(67.5^°)=I₀cos²(22.5^°)sin²(22.5^°)=I₀/4sin²(45^°)=I₀/8

Topic: Polarization, Brewster's law, Polaroids· Optics

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 polaroid, is (I_0 is the intensity of polarised light after passing through the first polaroid):

1. $\frac{I_0}{2}$

2. $\frac{I_0}{4}$

3. $\frac{I_0}{8}$

4. $\frac{I_0}{16}$

Doubtly Asked 30 Oct 2026 NEET UG 2025 Practice test neet Save WhatsApp Report

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Answer: 3. $\frac{I_0}{8}$

Key idea: apply Malus's law, $I=I_0\cos^2\theta$, at each polaroid.

The middle sheet is at $22.5^\circ$ to the first, and $90^\circ-22.5^\circ=67.5^\circ$ to the last (crossed) sheet.

$$I=I_0\cos^2(22.5^\circ)\cos^2(67.5^\circ)=I_0\cos^2(22.5^\circ)\sin^2(22.5^\circ)=\frac{I_0}{4}\sin^2(45^\circ)=\frac{I_0}{8}$$

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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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 polaroid, is (I_0 is the intensity of polarised light after passing through the first polaroid):

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