Wave Optics · JEE Main previous year questions

2025 14 questions

1. Q452025 · 8 Apr 2025 · Shift 2

   In a Young's double slit experiment, the source is white light. One of the slits is covered by red filter and another by a green filter. In this case:

   1. A.there shall be alternate interference fringes of red and green.
   2. B.there shall be an interference pattern for red distinct from that for green.
   3. C.there shall be an interference pattern, where each fringe's pattern center is green and outer edges is red.
   4. D.there shall be no interference fringes.
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   Answer: D

2. Q292025 · 4 Apr 2025 · Shift 1

   In a Young's double slit experiment, the slits are separated by 0.2 mm . If the slits separation is increased to 0.4 mm , the percentage change of the fringe width is :

   1. A.$25\%$
   2. B.$50\%$
   3. C.$0\%$
   4. D.$100\%$
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   Answer: B

3. Q402025 · 4 Apr 2025 · Shift 2

   Two polarisers $P_1$ and $P_2$ are placed in such a way that the intensity of the transmitted light will be zero. A third polariser $P_3$ is inserted in between $P_1$ and $P_2$, at particular angle between $P_2$ and $P_3$. The transmitted intensity of the light passing through all three polarisers is maximum. The angle between the polarisers $P_2$ and $P_3$ is :

   1. A.$\pi /6$
   2. B.$\frac{\pi }{3}$
   3. C.$\frac{\pi }{4}$
   4. D.$\pi /8$
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   Answer: C

4. Q502025 · 4 Apr 2025 · Shift 2· Numerical answer

   In a Young's double slit experiment, two slits are located $1.5\mathrm{mm}$ apart. The distance of screen from slits is $2\mathrm{m}$ and the wavelength of the source is $400\mathrm{nm}$ . If the 20 maxima of the double slit pattern are contained within the central maximum of the single slit diffraction pattern, then the width of each slit is $x\times 10^{-3}\mathrm{cm}$, where $x$-value is ____ .

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   Answer: 15

5. Q482025 · 3 Apr 2025 · Shift 1· Numerical answer

   Two coherent monochromatic light beams of intensities 4I and 9I are superimposed. The difference between the maximum and minimum intensities in the resulting interference pattern is $x\mathrm{I}$. The value of $x$ is____ .

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   Answer: 24

6. Q272025 · 3 Apr 2025 · Shift 2

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

   1. A.$8:1$
   2. B.$4:1$
   3. C.$3:1$
   4. D.$9:1$
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   Answer: B

7. Q322025 · 3 Apr 2025 · Shift 2

   Width of one of the two slits in a Young's double slit interference experiment is half of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is :

   1. A.$3:1$
   2. B.$(2\sqrt{2}+1):(2\sqrt{2}-1)$
   3. C.$9:1$
   4. D.$(3+2\sqrt{2}):(3-2\sqrt{2})$
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   Answer: D

8. Q492025 · 2 Apr 2025 · Shift 1· Numerical answer

   If the measured angular separation between the second minimum to the left of the central maximum and the third minimum to the right of the central maximum is $30^{\circ }$ in a single slit diffraction pattern recorded using $628\text{ nm}$ light, then the width of the slit is _________ $\mu \mathrm{m}$.

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   Answer: 6

9. Q502025 · 28 Jan 2025 · Shift 1· Numerical answer

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

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   Answer: 11

10. Q272025 · 24 Jan 2025 · Shift 1

    The Young's double slit interference experiment is performed using light consisting of 480 nm and 600 nm wavelengths to form interference patterns. The least number of the bright fringes of 480 nm light that are required for the first coincidence with the bright fringes formed by 600 nm light is

    1. A.8
    2. B.4
    3. C.5
    4. D.6
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    Answer: C

11. Q272025 · 24 Jan 2025 · Shift 2
    
    1. A.${\mathrm{I}}_0$
    2. B.$\frac{{\mathrm{I}}_0}{3}$
    3. C.$\frac{{\mathrm{I}}_0}{4}$
    4. D.$\frac{{\mathrm{I}}_0}{2}$
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    Answer: C

12. Q402025 · 24 Jan 2025 · Shift 2

    Young's double slit interference apparatus is immersed in a liquid of refractive index 1.44. It has slit separation of 1.5 mm . The slits are illuminated by a parallel beam of light whose wavelength in air is 690 nm . The fringe-width on a screen placed behind the plane of slits at a distance of 0.72 m , will be:

    1. A.0.63 mm
    2. B.0.33 mm
    3. C.0.46 mm
    4. D.0.23 mm
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    Answer: D

13. Q372025 · 23 Jan 2025 · Shift 2

    The width of one of the two slits in Young's double slit experiment is $\mathrm{d}$ while that of the other slit is $x\mathrm{d}$. If the ratio of the maximum to the minimum intensity in the interference pattern on the screen is $9:4$ then what is the value of $x$ ? (Assume that the field strength varies according to the slit width.)

    1. A.2
    2. B.3
    3. C.4
    4. D.5
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    Answer: D

14. Q442025 · 22 Jan 2025 · Shift 1

    Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion-(A) : If Young's double slit experiment is performed in an optically denser medium than air, then the consecutive fringes come closer. Reason-(R) : The speed of light reduces in an optically denser medium than air while its frequency does not change. In the light of the above statements, choose the most appropriate answer from the options given below :

    1. A.(A) is false but (R) is true
    2. B.Both (A) and (R) are true but (R) is not the correct explanation of (A)
    3. C.Both (A) and (R) are true and (R) is the correct explanation of (A)
    4. D.(A) is true but (R) is false
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    Answer: C