# Physics class 12th chapter 9 RAY OPTICS Most VVI Objective Question

Q.1. SI unit of power of a lens i

(A) joule

(B) diopter

(C) candela

(D) watt

Ans :- (B)

Q.2. The radius of curvature of plane mirror is

(A) infinite

(B) zero

(C) + 5cm

(D) – 5 cm

Ans :- (A)

Q.3. A bi-convex lens can form a virtual image if the object is placed

(A) between the lens and its focus

(B) at the focus

(C) between ƒand 2ƒ

(D) at infinity

Ans :- (A)

Q.4. The final image in astronomical telescope is

(A) real and erect

(B) real and inverted

(C) virtual and inverted

(D) virtual and erect

Ans :- (C)

Q.5. The critical angle of light passing from glass to air is minimum for

(A) Red colour

(B) Green colour

(C) Yellow colour

(D) Violet colour

Ans :- (D)

Q.6. Which of the following phenomena taken place when a monochromatic light in incident of a prism ?

(A) Dispersion

(B) Deviation

(C) Interference

(D) All of the above

Ans :- (A)

Q.7. When a ray of light enters a glass slab it’s wavelength

(A) decreases

(B) increases

(C) remains unchanged

(D) data are not complete

Ans :- (A)

Q.8. A bi-convex lens (μ-1.5) has equal curvature each of 20 cm. The power of the lens is

(A) 5D

(B) 10D

(C) 2.5 D

(D) 20 D

Ans :- (A)

Q.9. Cause of mirage is

(A) refraction and total internal reflection

(B) diffraction

(C) scattering

(D) interference

Ans :- (A)

Q.10. The focal length of a lens μ = 1.5 in air is 20 cm. Its focal length in medium of refractive index 1.5 is

(A) 20 cm.

(B) 40 cm.

(C) 10 cm.

(D) ∞

Ans :- (D)

Q.11. The image formed by objective lens of a compound microscope is

(A) Virtual and diminished

(B) Real and diminished

(C) Real and large

(D) Virtual and large

Ans :- (C)

Q.12. A convex lens is dipped in a liquid, whose refractive index is equal to refractive index of material of lens. Then its focal length will

(A) become zero

(B) become infinite

(C) decrease

(D) increase

Ans :- (B)

Q.13. When the tube length of microscope is increased, its magnifying power?

(A) increases

(B) decreases

(C) becomes zero

(D) remains unchanged

Ans :- (A)

Q.14. To remove hyper metropia lens used is

(A) Convex

(B) Concave

(C) Cylindrical

(D) Plano-convex

Ans :- (A)

Q.15. The upper half of a convex Lens is blackned,  size of image formed by it

(A) Increases

(B) Decreases

(C) Becomes of less intensity

(D) None of these

Ans :- (C)

Q.16. When concave lens of glass is immersed in water it works as

(A) Less convergent

(B) More convergent

(C) Less divergent

(D) More divergent

Ans :- (C)

Q.17. The minimum distance between an object and real image formed by conversing lens of focal length ƒ will be

(A) greater than 4ƒ

(B) less than 4ƒ

(C) equal to 2ƒ

(D) equal to 4ƒ

Ans :- (D)

Q.18. The angle of minimum Deviation for thin prism of refractive index (μ) is

(A) (1- μ)A

(B) (μ -1)A

(C) (μ +1)A

(D) (μ +1)A²

Ans :- (B)

Q.19. Critical angle for light moving from medium I to medium II is θ. The speed of light in medium I is ν. Then speed in medium II is

(A) ν(1-cosθ)

(B) ν/sinθ

(C) ν/cosθ

(D) ν(1-sinθ)

Ans :- (B)

Q.20. A magnifying glass is to be used at the fixed object distance of 1 inch. If it is to produce an erect image 5 items magnified, its focal length should be

(A) 0.2″

(B) 0.8″

(C) 1.25″

(D) 5″

Ans :- (C)

Q.21. The resolving power of human eye (in minute) is

(A) 1/60

(B) 1

(C) 10

(D) 1/2

Ans :- (B)

Q.22. Which has larger difference in focal length ?

(A) in telescope

(B) compound microscope

(C) in both

(D) None

Ans :- (A)

Q.23. The part of eye to see the size and colour of objects is

(A) iris

(B) eye lens

(C) optic nerves

(D) None of these

Ans :- (C)

Q.24. A virtual image larger than object is formed in a

(A) Convex mirror

(B) Concave mirror

(C) plane mirror

(D) Concave lens

Ans :- (B)

Q.25. The focal length of a lens does not depend upon

(A) refractive index of lens

(B) distance of object

(C) the two radii of curvature of the lens

(D) None of these

Ans :- (B)

Q.26. Given a point source of light, which of the following can produce a parallel beam of light?

(A) convex mirror

(B) concave mirror

(C) both ‘A’ and ‘B’

(D) none of these

Ans :- (B)

Q.27. A magnified virtual image can be formed by

(A) convex mirror

(B) concave mirror

(C) plane mirror

(D) concave lens

Ans :- (B)

Q.28. A diminished virtual image can be formed by

(A) plane mirror

(B) concave mirror

(C) convex mirror

(D) none of these

Ans :- (C)

Q.29. The vertically possible number of images of an object placed between two parallel mirrors is

(A) one

(B) two

(C) four

(D) infinite

Ans :- (D)

Q.30. The field of view is maximum for

(A) plane mirror

(B) concave mirror

(C) convex mirror

(D) none of these

Ans :- (C)

Q.31. A person sees the face in the mirror and finds big image, the mirror will be

(A) plane mirror

(B) concave mirror

(C) convex mirror

(D) none of these

Ans :- (B)

Q.32. focal length of plane mirror is

(A) zero

(B) infinity

(C) both ‘A’and’B’

(D) none of these

Ans :- (B)

Q.33. The power of the plane mirror is

(A) zero

(B) infinity

(C) unity

(D) none of these

Ans :- (A)

Q.34. The magnification of the plane mirror is

(A) zero

(B) infinity

(C) unity

(D) none of these

Ans :- (C)

Q.35. Refractive index is highest for

(A) water

(B) glass

(C) quartz

(D) diamond

Ans :- (D)

Q.36. The velocity of light is maximum is

(A) air

(B) glass

(C) water

(D) vacuum

Ans :- (D)

Q.37. Smell’s law does not hold for

(A) oblique incidence

(B) grazing incidence

(C) normal incidence

(D) none of these

Ans :- (C)

Q.38. When a ray of light passes through the optical centre of a lens it is

(A) deviated

(B) displaced

(C) deiviated and displaced

(D) none of these

Ans :- (B)

Q.39. The deviation of a ray of light produced by a prism depends on

(A) angle of prism only

(B) angle of incidence

(C) refractive index only

(D) all of above

Ans :- (D)

Q.40. If there were no atmosphere, then the length of day on the earth will be

(A) decrease

(B) remains the same

(C) increase

(D) none of these

Ans :- (A)

Q.41. A bubble of air inside water appears shining due to

(A) refraction

(B) reflection

(C) diffraction

(D) total internal reflection

Ans :- (D)

Q.42. The optical centre of a lens

(A) always lies with in the material of the lens

(B) always lies out side the material of the lens

(C) may lie inside, outside or on the surface of the lens

(D) always lies on the surface of the lens

Ans :- (C)

Q.43. A bio convex lens conform a virtual image if the object is placed

(A) at infinity

(B) at the focus

(C) between the lens and its focus

(D) none of these

Ans :- (C)

Q.44. A converging lens is that wich

(A) collects rays

(C) form real image only

(D) forms virtual image only

Ans :- (A)

Q.45. A well cut diamond sparkles due to its

(A) hardness

(B) high density

(C) large refractive index

(D) none of these

Ans :- (C)

Q.46. Myopia is corrected by the use of

(A) concave lens

(B) convex lens

(C) cylindrical lens

(D) none of these

Ans :- (A)

Q.47. The normal eye is most relaxed when it is focussed on an object at

(A) 25 mm away

(B) 25 cm away

(C) 25 m away

(D) infinity

Ans :- (D)

Q.48. Which of the following colour suffering by minimum deviation through the prism

(A) red

(B) violet

(C) green

(D) none of these

Ans :- (A)

Q.49. Sky appears blue due to

(A) refraction of light

(B) reflection of light

(C) dispersion of light

(D) scattering of light

Ans :- (D)

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