Ray Optics · JEE Main previous year questions

2021 16 questions

1. Q592021 · 26 Aug 2021 · Shift 2· Numerical answer
   
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   Answer: 50

2. Q322021 · 27 Jul 2021 · Shift 2
   
   1. A.
   2. B.
   3. C.
   4. D.
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   Answer: B

3. Q522021 · 27 Jul 2021 · Shift 2· Numerical answer

   The difference in the number of waves when yellow light propagates through air and vacuum columns of the same thickness is one. The thickness of the air column is __________ mm. [Refractive index of air = 1.0003, wavelength of yellow light in vacuum = $6000\text{ A˚}$]

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   Answer: 2

4. Q392021 · 25 Jul 2021 · Shift 1

   A ray of laser of a wavelength 630 nm is incident at an angle of $30^{\circ }$ at the diamond-air interface. It is going from diamond to air. The refractive index of diamond is 2.42 and that of air is 1. Choose the correct option.

   1. A.angle of refraction is $24.41^{\circ }$
   2. B.angle of refraction is $30^{\circ }$
   3. C.refraction is not possible
   4. D.angle of refraction is $53.4^{\circ }$
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   Answer: C

5. Q342021 · 25 Jul 2021 · Shift 2

   A prism of refractive index $\mu$ and angle of prism A is placed in the position of minimum angle of deviation. If minimum angle of deviation is also A, then the value of A in terms of refractive index is

   1. A.$2{\cos }^{-1}\left(\frac{\mu }{2}\right)$
   2. B.${\sin }^{-1}\left(\frac{\mu }{2}\right)$
   3. C.${\sin }^{-1}\left(\sqrt{\frac{\mu -1}{2}}\right)$
   4. D.${\cos }^{-1}\left(\frac{\mu }{2}\right)$
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   Answer: A

6. Q452021 · 25 Jul 2021 · Shift 2
   
   1. A.${\sin }^{-1}\frac{\sqrt{7}}{3}$
   2. B.${\sin }^{-1}\frac{\sqrt{5}}{4}$
   3. C.${\sin }^{-1}\frac{\sqrt{7}}{4}$
   4. D.${\sin }^{-1}\frac{\sqrt{5}}{3}$
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   Answer: A

7. Q432021 · 22 Jul 2021 · Shift 2
   
   1. A.${\sin }^{-1}(\tan r)$
   2. B.${\sin }^{-1}(\cot r)$
   3. C.${\sin }^{-1}(\tan r^{\prime })$
   4. D.${\tan }^{-1}(\sin i)$
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   Answer: A

8. Q512021 · 22 Jul 2021 · Shift 2· Numerical answer

   A ray of light passing through a prism ($\mu =\sqrt{3}$) suffers minimum deviation. It is found that the angle of incidence is double the angle of refraction within the prism. Then, the angle of prism is ________ (in degrees).

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   Answer: 60

9. Q532021 · 20 Jul 2021 · Shift 1· Numerical answer

   An object viewed from a near point distance of 25 cm, using a microscopic lens with magnification '6', gives an unresolved image. A resolved image is observed at infinite distance with a total magnification double the earlier using an eyepiece along with the given lens and a tube of length 0.6 m, if the focal length of the eyepiece is equal to __________ cm.

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   Answer: 25

10. Q372021 · 18 Mar 2021 · Shift 2
    
    1. A.green
    2. B.blue and green
    3. C.blue
    4. D.red
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    Answer: D

11. Q492021 · 18 Mar 2021 · Shift 2

    The speed of electrons in a scanning electron microscope is $1\times 10^7\mathrm{m}{\mathrm{s}}^{-1}$. If the protons having the same speed are used instead of electrons, then the resolving power of scanning proton microscope will be changed by a factor of :

    1. A.$\frac{1}{1837}$
    2. B.1837
    3. C.$\sqrt{1837}$
    4. D.$\frac{1}{\sqrt{1837}}$
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    Answer: B

12. Q362021 · 16 Mar 2021 · Shift 1
    
    1. A.Statements (B) and (C) are true
    2. B.Only statements (A) and (B) are true
    3. C.Statements (A), (B) and (C) are true
    4. D.Only statement (D) is true
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    Answer: C

13. Q362021 · 26 Feb 2021 · Shift 1

    A short straight object of height 100 cm lies before the central axis of a spherical mirror whose focal length has absolute value | f | = 40 cm. The image of object produced by the mirror is of height 25 cm and has the same orientation of the object. One may conclude from the information :

    1. A.Image is real, same side of convex mirror.
    2. B.Image is virtual, opposite side of convex mirror.
    3. C.Image is virtual, opposite side of concave mirror.
    4. D.Image is real, same side of concave mirror.
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    Answer: B

14. Q392021 · 26 Feb 2021 · Shift 2

    The incident ray, reflected ray and the outward drawn normal are denoted by the unit vectors $\vec{a},\vec{b}$ and $\vec{c}$ respectively. Then choose the correct relation for these vectors.

    1. A.$\vec{b}=\vec{a}+2\vec{c}$
    2. B.$\vec{b}=\vec{a}-2(\vec{a}\cdot \vec{c})\vec{c}$
    3. C.$\vec{b}=2\vec{a}+\vec{c}$
    4. D.$\vec{b}=\vec{a}-\vec{c}$
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    Answer: B

15. Q432021 · 26 Feb 2021 · Shift 2

    Given below are two statements : one is labeled as Assertion A and the other is labeled as Reason R. Assertion A : For a simple microscope, the angular size of the object equals the angular size of the image. Reason R : Magnification is achieved as the small object can be kept much closer to the eye than 25 cm and hence it subtends a large angle. In the light of the above statements, choose the most appropriate answer from the options given below :

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

16. Q572021 · 26 Feb 2021 · Shift 2· Numerical answer
    
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    Answer: 150