Ray Optics · JEE Main previous year questions

2019 18 questions

1. Q392019 · 12 Apr 2019 · Shift 1

   The value of numerical aperature of the objective lens of a microscope is 1.25. If light of wavelength $5000\text{ A˚}$ is used, the minimum separation between two points, to be seen as distinct, will be :

   1. A.$0.12\mu \text{m}$
   2. B.$0.38\mu \text{m}$
   3. C.$0.24\mu \text{m}$
   4. D.$0.48\mu \text{m}$
   Show answer

   Answer: C

2. Q512019 · 12 Apr 2019 · Shift 1
   
   1. A.11.7 cm
   2. B.6.7 cm
   3. C.13.4 cm
   4. D.8.8 cm
   Show answer

   Answer: D

3. Q332019 · 12 Apr 2019 · Shift 2
   
   1. A.$\theta >{\sin }^{-1}\sqrt{\frac{{\mu }_2^2}{{\mu }_1^2}-1}$
   2. B.$\theta <{\sin }^{-1}\sqrt{\frac{{\mu }_2^2}{{\mu }_1^2}-1}$
   3. C.$\theta <{\sin }^{-1}\frac{{\mu }_1}{{\mu }_2}$
   4. D.$\theta >{\sin }^{-1}\frac{{\mu }_1}{{\mu }_2}$
   Show answer

   Answer: B

4. Q342019 · 10 Apr 2019 · Shift 1
   
   1. A.$\frac{2R}{{\mu }_1-{\mu }_2}$
   2. B.$\frac{R}{2-({\mu }_1-{\mu }_2)}$
   3. C.$\frac{R}{{\mu }_1-{\mu }_2}$
   4. D.$\frac{R}{2({\mu }_1-{\mu }_2)}$
   Show answer

   Answer: C

5. Q542019 · 10 Apr 2019 · Shift 2
   
   1. A.$\frac{b^2}{ac}$
   2. B.$\frac{b^{2}c}{a}$
   3. C.$\frac{a}{c}$
   4. D.$\frac{b}{c}$
   Show answer

   Answer: D

6. Q572019 · 9 Apr 2019 · Shift 1

   A concave mirror for face viewing has focal length of 0.4 m. The distance at which you hold the mirror from your face in order to see your image upright with a magnification of 5 is :

   1. A.0.24 m
   2. B.0.32 m
   3. C.1.60 m
   4. D.0.16 m
   Show answer

   Answer: B

7. Q352019 · 9 Apr 2019 · Shift 2
   
   1. A.$\sqrt{3}$
   2. B.$3/2$
   3. C.$\sqrt{2}$
   4. D.$4/3$
   Show answer

   Answer: D

8. Q402019 · 9 Apr 2019 · Shift 2

   A convex lens of focal length 20 cm produces images of the same magnification 2 when an object is kept at two distances $x_1$ and $x_2$ $(x_1>x_2)$ from the lens. The ratio of $x_1$ and $x_2$ is :-

   1. A.3 : 1
   2. B.2 : 1
   3. C.5 : 3
   4. D.4 : 3
   Show answer

   Answer: A

9. Q412019 · 9 Apr 2019 · Shift 2

   Diameter of the objective lens of a telescope is 250 cm. For light of wavelength 600nm. coming from a distant object, the limit of resolution of the telescope is close to :-

   1. A.$3.0\times 10^{-7}\mathrm{rad}$
   2. B.$4.5\times 10^{-7}\mathrm{rad}$
   3. C.$1.5\times 10^{-7}\mathrm{rad}$
   4. D.$2.0\times 10^{-7}\mathrm{rad}$
   Show answer

   Answer: A

10. Q442019 · 9 Apr 2019 · Shift 2

    $50W/{\mathrm{m}}^2$ energy density of sunlight is normally incident on the surface of a solar panel. Some part of incident energy (25%) is reflected from the surface and the rest is absorbed. The force exerted on $1{\mathrm{m}}^2$ surface area will be close to $(c=3\times 10^{8}m/s)$ :-

    1. A.$20\times 10^{-8}\mathrm{N}$
    2. B.$35\times 10^{-8}\mathrm{N}$
    3. C.$10\times 10^{-8}\mathrm{N}$
    4. D.$15\times 10^{-8}\mathrm{N}$
    Show answer

    Answer: A

11. Q362019 · 8 Apr 2019 · Shift 2

    Calculate the limit of resolution of a telescope objective having a diameter of 200 cm, if it has to detect light of wavelength 500 nm coming from a star :-

    1. A.$610\times 10^{-9}$ radian
    2. B.$457.5\times 10^{-9}$ radian
    3. C.$305\times 10^{-9}$ radian
    4. D.$152.5\times 10^{-9}$ radian
    Show answer

    Answer: C

12. Q482019 · 8 Apr 2019 · Shift 2

    A convex lens (of focal length 20 cm) and a concave mirror, having their principal axes along the same lines, are kept 80 cm apart from each other. The concave mirror is to the right of the convex lens. When an object is kept at a distance of 30 cm to the left of the convex lens, its image remains at the same position even if the concave mirror is removed. The maximum distance of the object for which this concave mirror, by itself would produce a virtual image would be :-

    1. A.25 cm
    2. B.10 cm
    3. C.20 cm
    4. D.30 cm
    Show answer

    Answer: B

13. Q392019 · 12 Jan 2019 · Shift 1
    
    1. A.d
    2. B.d/2
    3. C.3d
    4. D.2d
    Show answer

    Answer: C

14. Q502019 · 12 Jan 2019 · Shift 1
    
    1. A.$\frac{20}{3}\mathrm{cm}$ from point B at right, real
    2. B.$70\mathrm{cm}$ from point B at right ; real
    3. C.$40\mathrm{cm}$ from point B at right; real
    4. D.$70\mathrm{cm}$ from point B at left ; virtual
    Show answer

    Answer: B

15. Q382019 · 12 Jan 2019 · Shift 2

    A plano-convex lens (focal length $f_2$, refractive index ${\mu }_2$, radius of curvature R) fits exactly into a plano-concave lens (focal length $f_1$, refractive index ${\mu }_1$, radius of curvature R). Their plane surfaces are parallel to each other. Then, the focal length of the combination will be :

    1. A.$f_1+f_2$
    2. B.$f_1-f_2$
    3. C.$\frac{R}{{\mu }_2-{\mu }_1}$
    4. D.$\frac{2f_1{f}_2}{f_1+f_2}$
    Show answer

    Answer: C

16. Q552019 · 12 Jan 2019 · Shift 2
    
    1. A.Image disappears
    2. B.Magnified image
    3. C.Erect real image
    4. D.No change
    Show answer

    Answer: A

17. Q442019 · 11 Jan 2019 · Shift 2

    A monochromatic light is incident at a certain angle on an equilateral triangular prism and suffers minimum deviation. If the refractive index of the material of the prism is $\sqrt{3}$, then the angle of incidence is:

    1. A.$60^{\circ }$
    2. B.$45^{\circ }$
    3. C.$90^{\circ }$
    4. D.$30^{\circ }$
    Show answer

    Answer: A

18. Q332019 · 9 Jan 2019 · Shift 1

    A convex lens is put 10 cm from a light source and it makes a sharp image on a screen, kept 10 cm from the lens. Now a glass block (refractive index 1.5) of 1.5 cm thickness is placed in contact with the light source. To get the sharp image again, the screen is shifted by a distance d. Then d is :

    1. A.1.1 cm away from the lens
    2. B.0
    3. C.0.55 cm towards the lens
    4. D.0.55 cm away from the lens
    Show answer

    Answer: D