A parallel beam of light of intensity I₀ is incident on a glass plate, 25% of light is reflected by upper surface ( I₁) and 50% of light is reflected from lower surface ( I₂). The ratio I₂ to I₁ is (a) 1: 4 (b) 3: 2 (c) 2: 3 (d) 4: 1

Answer: (b). Upper surface reflects I₁ = 0.25I₀; 0.75I₀ enters the plate. Lower surface reflects 50% of this: I₂ = 0.375I₀. (I₂)/(I₁) = (0.375)/(0.25) = 3/2. So the answer is (b) 3: 2.

A parallel beam of light of intensity I₀ is incident on a glass… | MHT CET 2026 (14 May, Shift 1)

Q8MHT CET 2026 · 14 MAY · SHIFT 1Medium

Biprism, Thin Films & Other Devices

A parallel beam of light of intensity $I_0$ is incident on a glass plate, $25\%$ of light is reflected by upper surface ( $I_1$ ) and $50\%$ of light is reflected from lower surface ( $I_2$ ). The ratio $I_2$ to $I_1$ is

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Answer: (b)

Upper surface reflects $I_1 = 0.25I_0$ ; $0.75I_0$ enters the plate.
Lower surface reflects $50\%$ of this: $I_2 = 0.375I_0$ .
$\frac{I_2}{I_1} = \frac{0.375}{0.25} = \frac{3}{2}$ . So the answer is (b) $3 : 2$ .

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