Of the two slits producing interference in Young's experiment, one is covered with glass so that light intensity passing is reduced to 50%. Which of the following is correct? (a) Intensity of fringes remains unaltered. (b) Intensity of bright fringe decreases and that of dark fringe increases. (c) Intensity of bright fringe increases and that of dark fringe decreases. (d) Intensity of both bright and dark fringes decreases.

Answer: (b). Originally I₁ = I₂ = I: Imax = 4I, Imin = 0. Now I and 0.5I: Imax = (1+√(0.5))² I ≈ 2.91I, Imin = (1-√(0.5))² I ≈ 0.09I. Bright fringes get dimmer, dark fringes get brighter. So the answer is (b).

Of the two slits producing interference in Young's experiment, one is… | MHT CET 2023 (13 May, Shift 2)

Q58MHT CET 2023 · 13 MAY · SHIFT 2Medium

Superposition, Coherence & Intensity

Of the two slits producing interference in Young's experiment, one is covered with glass so that light intensity passing is reduced to $50\%$ . Which of the following is correct?

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Answer: (b)

Originally $I_1 = I_2 = I$ : $I_{max} = 4I$ , $I_{min} = 0$ .
Now $I$ and $0.5I$ : $I_{max} = (1+\sqrt{0.5})^2 I \approx 2.91I$ , $I_{min} = (1-\sqrt{0.5})^2 I \approx 0.09I$ .
Bright fringes get dimmer, dark fringes get brighter. So the answer is (b).

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