# MCQ | Ray Optics

QUIZ TEST – I

Question:1. If the behavior of light rays through a convex lens is as shown in the adjoining figure, then; (A) μ = μ2

(B) μ < μ2

(C) μ > μ2

(D) μ ≤ μ2

Ans: (B)

Question:2. A ray of light is incident at the glass-water interface at an angle i , it emerges finally parallel to the surface of water, then the value of μg would be (A) (4/3)sin(i)

(B) [1/sin(i)]

(C) 4/3

(D) 1

Ans: (B)

Question:3. A converging lens is used to form an image on a screen. When the upper half of the lens is covered by an opaque screen :

(A) half of the image will disappear

(B) image will not form on the screen.

(C) intensity of image will increase

(D) intensity of image will decrease

Ans: (D)

Question:4. A spherical convex surface separates object and image space of refractive index 1 and 4/3 respectively. If radius of curvature of the surface is 0.1 m, its power is :

(A) 2.5 D

(B) -2.5 D

(C) 3.3 D

(D) -3.3 D

Ans: (A)

Question:5.  A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and latter is equal to 3/4th the angle of prism. The angle of deviation is :

(A) 45o

(B) 39o

(C) 20o

(D) 30o

Ans: (D)

Question:6. A liquid is placed in a hollow prism of angle 60o. If angle of the minimum deviation is 30o, what is the refractive index of the liquid?

(A) 1.41

(B) 1.50

(C) 1.65

(D) 1.95

Ans: (A)

Question:7.  A prism can produce a minimum deviation d in a light beam. If three such prisms are combined, the minimum deviation that can be produced in this beam is:

(A) 0

(B) δ

(C) 2δ

(D) 3δ

Ans: (B)

Question:8. The face PR of a prism QPR of angle 30o is silvered. A ray is incident on face PQ at an angle of 45o as shown in figure. The refracted ray undergoes reflection on face PR and retraces its path. The refractive index of the prism is : (A) √2

(B) 3/√2

(C) 1.5

(D) 1.33

Ans: (A)

Question:9. A particle moves towards a concave mirror of focal length 30 cm along its axis and with a constant speed of 4 cm/ sec. What is the speed of its image when the particle is at 90 cm from the mirror?

(A) 2 cm/ sec.

(B) 8 cm/sec.

(C) 1 cm/sec.

(D) 4 cm/sec.

Ans: (C)

Question:10. A thin prism of glass is placed in air and water successively. If aμg = 3/2 and aμw = 4/3, then the ratio of deviations produced by the prism for a small angle of incidence when placed in air and water is :

(A) 9 : 8

(B) 4 : 3

(C) 3 : 4

(D) 4 : 1

Ans: (D)

Question:11.  A thin prism P1 with angle 4o and made from glass of refractive index 1.54 is combined with another thin prism P2 made from glass of refractive index 1.72 to produce dispersion without deviation. The angle of the prism P2 is :

(A) 5.33o

(B) 4o

(C) 3o

(D) 2.6o

Ans: (C)

Question:12. Focal lengths of two lenses are f and f’ and dispersive powers of their materials are ω and ω’. To form achromatic combination from these, which relation is correct ?

(A) ω = ω0 , ω’ = 2ω0, f’ = 2f

(B) ω = ω0, ω’ = 2ω0, f’ = -2f

(C) ω = ω0 , ω’ = 2ω0, f’ = f/2

(D) ω = ω0, ω’ = 2ω0 , f’ = -f/2

Ans: (B)

Question:13. A lens of refractive index μ is put in a liquid of refractive index μ’ . If the focal length of the lens in air is f, its focal length in liquid will be

(A) $\large \frac{-f \mu'(\mu -1)}{\mu’ -\mu}$

(B) $\large \frac{f (\mu’ -\mu)}{\mu'(\mu -1)}$

(C) $\large \frac{\mu'(\mu -1)}{f (\mu’ -\mu) }$

(D) $\large \frac{f (\mu’ \mu)}{(\mu -\mu’)}$

Ans: (A)

Question:14. A convex lens, a glass slab, a glass prism and a spherical solid ball have been prepared from the same optically transparent material. Dispersive power will be possessed by:

(A) the prism only

(B) the convex lens and the prism

(C) all except glass slab.

(D) all the four

Ans: (C)

Question:15.  A beam of white light is incident on a hollow prism of glass as shown in the figure. Then (A) The light emerging from prism gives no spectrum

(B) The light emerging from prism gives spectrum but the bending of all colours is away from base.

(C) The light emerging from prism gives spectrum, all the colours bend towards base, the violet most and red the least.

(D) The light emerging from prism gives spectrum, all the colours bend towards base, the violet the least and red the most.

Ans: (A)

Question:16. A beam of light consisting of red, green and blue colours is incident on a right-angled prism. The refractive indices of the material of prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47 respectively. The prism will: (A) separate part of the red colour from the green and blue colours

(B) separate part of the blue colour from the red and green colours

(C) separate all the three colours from one another

(D) not separate even partially any colour from the other two colours.

Ans: (A)

Question:17. A convex lens A of focal length 20 cm and a concave lens B of focal length 5 cm are kept along the same axis with a distance d between them. If a parallel beam of light falling on A leaves B as a parallel beam, then the distance d in cm will be:

(A) 25

(B) 15

(C) 10

(D) 30

Ans: (B)

Question:18. When the distance between the object and the screen is more than 4f, we can obtain the image of the object on the screen for the two different positions of a convex lens of focal length f. If I1 and I2 be the sizes of the two images, then the size of the object is:

(A) (I1 + I2)/2

(B) I1 – I2

(C) $\sqrt{I_1 I_2}$

(D) $\sqrt{I_1 / I_2}$

Ans: (C)

Question:19.  A layered lens as shown in the figure is made of two types of transparent materials indicated by different shades. A point object is placed on its axis. The object will form: (A) 1 image

(B) 2 images

(C) 3 images

(D) 7 images

Ans: (B)

Question:20. In the displacement method, a convex lens is placed in between an object and a screen. If the magnification in the two positions be m1 and m2 and the displacement of the lens between the two positions is X, then the focal length of the lens is :

(A) X/(m1 × m2)

(B) X/|m1 – m2 |

(C) X/|m1 + m2 |

(D) X/(m1 – m2)2