Wave Optics · JEE Main previous year questions

2022 12 questions

1. Q392022 · 29 Jul 2022 · Shift 2

   An unpolarised light beam of intensity $2I_0$ is passed through a polaroid P and then through another polaroid Q which is oriented in such a way that its passing axis makes an angle of $30^{\circ }$ relative to that of P. The intensity of the emergent light is

   1. A.$\frac{I_0}{4}$
   2. B.$\frac{I_0}{2}$
   3. C.$\frac{3I_0}{4}$
   4. D.$\frac{3I_0}{2}$
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   Answer: C

2. Q522022 · 28 Jul 2022 · Shift 1· Numerical answer

   In a Young's double slit experiment, a laser light of 560 nm produces an interference pattern with consecutive bright fringes' separation of 7.2 mm. Now another light is used to produce an interference pattern with consecutive bright fringes' separation of 8.1 mm. The wavelength of second light is __________ nm.

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   Answer: 630

3. Q532022 · 27 Jul 2022 · Shift 1· Numerical answer

   Two beams of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the two beams are $\pi /2$ and $\pi /3$ at points A and B respectively. The difference between the resultant intensities at the two points is $xI$. The value of $x$ will be _________.

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   Answer: 2

4. Q442022 · 27 Jul 2022 · Shift 2

   Two coherent sources of light interfere. The intensity ratio of two sources is $1:4$. For this interference pattern if the value of $\frac{I_{\max }+I_{\min }}{I_{\max }-I_{\min }}$ is equal to $\frac{2\alpha +1}{\beta +3}$, then $\frac{\alpha }{\beta }$ will be :

   1. A.1.5
   2. B.2
   3. C.0.5
   4. D.1
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   Answer: B

5. Q332022 · 26 Jul 2022 · Shift 1

   In Young's double slit experiment, the fringe width is $12\mathrm{mm}$. If the entire arrangement is placed in water of refractive index $\frac{4}{3}$, then the fringe width becomes (in mm):

   1. A.16
   2. B.9
   3. C.48
   4. D.12
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   Answer: B

6. Q452022 · 30 Jun 2022 · Shift 1

   Find the ratio of maximum intensity to the minimum intensity in the interference pattern if the widths of the two slits in Young's experiment are in the ratio of 9 : 16. (Assuming intensity of light is directly proportional to the width of slits)

   1. A.3 : 4
   2. B.4 : 3
   3. C.7 : 1
   4. D.49 : 1
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   Answer: D

7. Q462022 · 28 Jun 2022 · Shift 2

   In Young's double slit experiment performed using a monochromatic light of wavelength $\lambda$, when a glass plate ($\mu =1.5$) of thickness $\mathrm{x}\lambda$ 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 x will be :

   1. A.3
   2. B.2
   3. C.1.5
   4. D.0.5
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   Answer: B

8. Q532022 · 28 Jun 2022 · Shift 2· Numerical answer

   In a Young's double slit experiment, an angular width of the fringe is $0.35^{\circ }$ on a screen placed at $2\mathrm{m}$ away for particular wavelength of $450\mathrm{nm}$. The angular width of the fringe, when whole system is immersed in a medium of refractive index $7/5$, is $\frac{1}{\alpha }$. The value of $\alpha$ is ____.

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   Answer: 4

9. Q522022 · 27 Jun 2022 · Shift 1· Numerical answer

   In Young's double slit experiment the two slits are 0.6 mm distance apart. Interference pattern is observed on a screen at a distance 80 cm from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light will be ____________ nm.

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   Answer: 450

10. Q432022 · 25 Jun 2022 · Shift 1

    The two light beams having intensities $\mathrm{I}$ and $9\mathrm{I}$ interfere to produce a fringe pattern on a screen. The phase difference between the beams is $\pi /2$ at point $\mathrm{P}$ and $\pi$ at point $\mathrm{Q}$. Then the difference between the resultant intensities at $\mathrm{P}$ and $\mathrm{Q}$ will be :

    1. A.$2\mathrm{I}$
    2. B.$6\mathrm{I}$
    3. C.$5\mathrm{I}$
    4. D.$7\mathrm{I}$
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    Answer: B

11. Q492022 · 25 Jun 2022 · Shift 1

    Given below are two statements : Statement I : Davisson-Germer experiment establishes the wave nature of electrons. Statement II : If electrons have wave nature, they can interfere and show diffraction. In the light of the above statements choose the correct answer from the option given below :

    1. A.Both Statement I and Statement II are true.
    2. B.Both Statement I and Statement II are false.
    3. C.Statement I is true but Statement II is false.
    4. D.Statement I is false but Statement II is true.
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    Answer: A

12. Q442022 · 25 Jun 2022 · Shift 2

    The interference pattern is obtained with two coherent light sources of intensity ratio $4:1$. And the ratio $\frac{I_{\max }+I_{\min }}{I_{\max }-I_{\min }}$ is $\frac{5}{x}$. Then, the value of x will be equal to :

    1. A.3
    2. B.4
    3. C.2
    4. D.1
    Show answer

    Answer: B