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Fringe shift when a thin transparent sheet covers one slit

This type of question, asked 7 times: 28 Jun 2022, 30 Jan 2023, 1 Feb 2023, 9 Apr 2024, 21 Jan 2026 S1, 21 Jan 2026 S2, 4 Apr 2026 S2. All 7 questions below, oldest first.

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  1. Question 1

    28 Jun 2022

    106
    In young's double slit experiment performed using a monochromatic light of wavelength λ\lambda, when a glass plate (μ=1.5)(\mu = 1.5) of thickness xλx\lambda is introduced in the path of the one of the interfering beams, the intensity at the position where the central maximum occurred previously remains unchanged. The value of xx will be:

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  2. Question 2

    30 Jan 2023

    28
    In Young's double slit experiment, two slits S1S_{1} and S2S_{2} are ' dd ' distance apart and the separation from slits to screen is D (as shown in figure). Now if two transparent slabs of equal thickness 0.1 mm0.1\text{ }mm but refractive index 1.51 and 1.55 are introduced in the path of beam (λ=4000Å)(\lambda = 4000\text{Å}) from S1S_{1} and S2S_{2} respectively. The central bright fringe spot will shift by ____\_\_\_\_ fringes.

  3. Question 3

    1 Feb 2023

    113
    As shown in the figure, in Young's double slit experiment, a thin plate of thickness t=10μmt = 10\mu m and refractive index μ=1.2\mu = 1.2 is inserted in front of slit S1S_{1}. The experiment is conducted in air (μ=1)(\mu = 1) and uses a monochromatic light of wavelength λ=500 nm\lambda = 500\text{ }nm. Due to the insertion of the plate, central maxima is shifted by a distance of xβ0x\beta_{0}, where β0\beta_{0} is the fringe-width before the insertion of the plate. The value of the xx is

  4. Question 4

    9 Apr 2024

    118
    Monochromatic light of wavelength 500 nm500\text{ }nm is used in Young's double slit experiment. An interference pattern is obtained on a screen. When one of the slits is covered with a very thin glass plate (refractive index =1.5= 1.5 ), the central maximum is shifted to a position previously occupied by the 4th 4^{\text{th~}} bright fringe. The thickness of the glass-plate is ______ μm\mu m.

  5. Question 5

    21 Jan 2026 S1

    11
    In a double slit experiment the distance between the slits is 0.1 cm and the screen is placed at 50 cm from the slits plane. When one slit is covered with a transparent sheet having thickness tt and refractive index n(=1.5)n( = 1.5), the central fringe shifts by 0.2 cm. The value of t is ____\_\_\_\_ cm.

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  6. Question 6

    21 Jan 2026 S2

    24
    In a Young's double slit experiment set up, the two slits are kept 0.4 mm0.4\text{ }mm apart and screen is placed at 1 m from slits. If a thin transparent sheet of thickness 20μ m20\mu\text{ }m is introduced in front of one of the slits then central bright fringe shifts by 20 mm on the screen. The refractive index of transparent sheet is given by α10\frac{\alpha}{10}, where α\alpha is ____\_\_\_\_ .

  7. Question 7

    4 Apr 2026 S2

    25
    In a double slit experiment, when one of the slits is covered by a transparent mica sheet of refractive index 1.56, the central fringe shifts to the position of 7th 7^{\text{th~}} bright fringe, obtained with both slits uncovered. If the light source wavelength is 450 nm , the thickness of mica sheet is α×10−9 m\alpha \times 10^{- 9}\text{ }m. The value of α\alpha is ____\_\_\_\_ .