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Wave Optics

JEE Mains Physics. Try each one first, then open its answer.

Top 10 JEE Mains PYQs to practise first

The questions and kinds of question asked most often come first. Each one says how often and in which papers.

  1. Question 1

    This type asked 10 times: 15 Apr 2023, 27 Jan 2024, 29 Jan 2024, 30 Jan 2024, 1 Feb 2024, 5 Apr 2024, 8 Apr 2024, 2 Apr 2025, 2 Apr 2026 S1, 4 Apr 2026 S1. This one: 4 Apr 2026 S1 See all 10 of this type

    8
    A slit of width a is illuminated by light of wavelength λ\lambda. The linear separation between 1st 1^{\text{st~}} and 3rd 3^{\text{rd~}} minima in the diffraction pattern produced on a screen placed at a distance D from the slit system is ____\_\_\_\_ .

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  2. Question 2

    This type asked 8 times: 30 Jan 2023, 10 Apr 2023, 29 Jan 2024, 1 Feb 2024, 9 Apr 2024, 2 Apr 2026 S2, 6 Apr 2026 S1, 6 Apr 2026 S2. This one: 6 Apr 2026 S2 See all 8 of this type

    20
    In a Young double slit experiment, the wavelength of the incident light is 6000Å6000\text{Å}, the separation between slits S1S_{1} and S2S_{2} is 5 cm, the distance between slits plane and screen is 50 cm , as shown in the figure below. If the resultant intensity at P is equal to the intensity due to individual slits, the path difference between interfering waves is ____\_\_\_\_ Å.

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  3. Question 3

    This type asked 8 times: 2021 Paper 3, 2021 Paper 21, 14 Jun 2022, 25 Jun 2022, 27 Jul 2022, 13 Apr 2023, 6 Apr 2024, 3 Apr 2025. This one: 3 Apr 2025 See all 8 of this type

    81
    Two monochromatic light beams have intensities in the ratio 1:91:9. An interference pattern is obtained by these beams. The ratio of the intensities of maximum to minimum is.

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  4. Question 4

    This type 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. This one: 4 Apr 2026 S2 See all 7 of this type

    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 ____\_\_\_\_ .

  5. Question 5

    This type asked 6 times: 29 Jan 2023, 31 Jan 2023, 10 Apr 2023, 27 Jan 2024, 4 Apr 2025, 4 Apr 2026 S2. This one: 4 Apr 2026 S2 See all 6 of this type

    17
    An unpolarized light of certain intensity passes through a combination of two polarizers whose transmission axes are at 30∘30^{\circ} and 90∘90^{\circ}, respectively, with respect to the horizontal axis. A third polarizer with its transmission axis at 60∘60^{\circ} with the horizontal axis is placed between the two existing polarizers. The ratio of the output intensities with and without the third polarizer is ____\_\_\_\_.

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  6. Question 6

    This type asked 6 times: 2021 Paper 9, 2021 Paper 23, 2021 Paper 25, 25 Jan 2023, 5 Apr 2024, 28 Jan 2025. This one: 28 Jan 2025 See all 6 of this type

    25
    A double slit interference experiment performed with a light of wavelength 600 nm forms an interference fringe pattern on a screen with 10th 10^{\text{th~}} bright fringe having its centre at a distance of 10 mm from the central maximum. Distance of the centre of the same 10th 10^{\text{th~}} bright fringe from the central maximum when the source of light is replaced by another source of wavelength 660 nm would be _____\_\_\_\_\_ mm .

  7. Question 7

    This type asked 5 times: 27 Jun 2022, 29 Jan 2023, 29 Jan 2024, 24 Jan 2026 S2, 5 Apr 2026 S2. This one: 5 Apr 2026 S2 See all 5 of this type

    17
    The maximum intensity in a Young's double slit experiment is I0I_{0}. Distance between the slits (d) is 5λ5\lambda, where λ\lambda is the wavelength of light used. The intensity of the fringe, exactly opposite to one of the slits on the screen, placed at D=10 dD = 10\text{ }d is ____\_\_\_\_

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  8. Question 8

    This type asked 5 times: 28 Jun 2022, 26 Jul 2022, 22 Jan 2025, 24 Jan 2025, 5 Apr 2026 S1. This one: 5 Apr 2026 S1 See all 5 of this type

    14
    In Young's double slit experiment, the fringes width of the interferences pattern produced on the screen is 2.4μ m2.4\mu\text{ }m. If the experiment is carried out in another medium having refractive index 1.2, the fringe width will be ____\_\_\_\_ μm\mu m.

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  9. Question 9

    This type asked 5 times: 31 Jan 2023, 6 Apr 2023, 4 Apr 2024, 24 Jan 2025, 28 Jan 2026 S2. This one: 28 Jan 2026 S2 See all 5 of this type

    24
    A beam of light consisting of wavelengths 650 nm and 550 nm illuminates the Young's double slits with separation of 2 mm such that the interference fringes are formed on a screen, placed at a distance of 1.2 m from the slits. The least distance of a point from the central maximum, where the bright fringes due to both the wavelengths coincide, is ____\_\_\_\_ ×10−5 m\times 10^{- 5}\text{ }m.

  10. Question 10

    This type asked 5 times: 29 Jun 2022, 28 Jul 2022, 8 Apr 2023, 4 Apr 2025, 23 Jan 2026 S1. This one: 23 Jan 2026 S1 See all 5 of this type

    24
    In two separate Young's double-slit experimental set-ups, two monochromatic light sources of different wavelengths are used to get fringes of equal width. The ratios of the slit separations and that of the wavelengths of light used are 2:12:1 and 1:21:2 respectively. The corresponding ratio of the distances between the slits and the respective screens ( D1/D2D_{1}/D_{2} ) is ____\_\_\_\_.