Light waves from two coherent sources arrive at two points on a screen with path difference of zero and (λ)/(2). The ratio of intensities at the points is (cos 0° = 1, cos π = -1) (a) 2: 1 (b) 1: 1 (c) 1: 2 (d) ∞: 1

Answer: (d). For equal coherent waves I = Imaxcos ²φ/2. Δ x = 0: I₁ = Imax. Δ x = λ/2: φ = π, I₂ = 0 (dark fringe). I₁: I₂ = Imax: 0 = ∞: 1. So the answer is (d).

Light waves from two coherent sources arrive at two points on a… | MHT CET 2023 (10 May, Shift 2)

Q62MHT CET 2023 · 10 MAY · SHIFT 2Medium

Superposition, Coherence & Intensity

Light waves from two coherent sources arrive at two points on a screen with path difference of zero and $\frac{\lambda}{2}$ . The ratio of intensities at the points is $(\cos 0^\circ = 1, \cos \pi = -1)$

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Answer: (d)

For equal coherent waves $I = I_{max}\cos^2\dfrac{\phi}{2}$ .
$\Delta x = 0$ : $I_1 = I_{max}$ . $\Delta x = \lambda/2$ : $\phi = \pi$ , $I_2 = 0$ (dark fringe).
$I_1 : I_2 = I_{max} : 0 = \infty : 1$ . So the answer is (d).

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Superposition, Coherence & Intensity question from MHT CET 2023 (10 May, Shift 2)

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