physical optics for instruments important bits

QUIZ-BITS

CHAPTER-I

PHYSICAL OPTICS FOR INSTRUMENTS

1.1. Interference of light

1. In geometrical optics the wavelength of light is __________.

a) less than the object size.

b) greater than the object size.

c) negligible when compared to the object size.

d) equal to the object size.

2. When the wavelength of light is negligible compared with the dimensions of an

optical system , then such an optics is called

a) Physical optics

b) Geometrical optics

c) a & b

d) None of the above

3. When a light ray is propagating in space from one point to the other in a straight line,

then such optics is known as

a) Physical optics


c) a & b


4. In physical optics the wavelength of light is ___________.

a) greater than the relevant components of optical system.

b) comparable to the relevant components of optical system.

c) negligible when compared to the relevant components of optical system.

d) none of the above

5. When the wavelength of light is not ignored compared with the dimensions of an

optical system , then such optics is called as

a) Physical optics


c) a & b


6. Light waves are __________.

a) electromagnetic waves

b) Beta rays

c) Gamma rays

d) Infrared rays

7. The electromagnetic waves travel with a velocity __________.

a) equal to the velocity of water waves

b) equal to the velocity of light

c) equal to the velocity of electrons

d) equal to the velocity of protons

8. Corpuscular theory of light was proposed by __________.

a) Newton

b) Einstein

c) Huygens

d) Dirac

9. Wave theory of light was proposed by ____________.

a) Newton

b) Einstein

c) Huygens

d) Dirac

10. With the help of corpuscular theory one cannot explain ____________.

a) reflection of light

b) diffraction of light

c) interference of light

d) both (b) and (c)

11. The following phenomenon can give evidence about the wave nature of light

a) Photoelectric effect

b) Interference

c) blackbody radiation


12. Wave theory of light was proposed to explain ____________.

a) The reflection and the refraction of light.

b) The interference and diffraction of light.

c) Polarization of light.

d) both (b) and (c)

13. Light rays travel in straight lines because ____________.

a) it consists small particles

b) the wavelength of light is very small

c) the velocity of light is very small

d) it consists of waves

14. The properties of light can be explained by ____________.

a) Wave theory of light

b) Corpuscular theory of light

c) both (a) and (b)


15. The nature of light is ____________.

a) Waves like

b) Particle like

c) both particle and wave like


16. In Huygens wave theory the concept of secondary wavelets allows us to find

____________.

a) refractive index of the medium

b) the velocity of light

c) interference of light

d) position of wave front

17. The process of constructing new wavefront from secondary wavelets is known as

____________.

a) Refraction

b) Propagation

c) Newtons principle

d) Huygens principle

18. To explain Compton Effect and photoelectric effect light is treated as stream of particles

known as ____________.

a) photons

b) phonons

c) electrons

d) protons

19. The following concepts can be used to understand the interference of light.

a) Coherence

b) The principal of superposition

c) a& b


20. Interference pattern is characterized by

a) Bright and dark fringes are equally spaced

b) all bright fringes are equally bright

c)all dark fringes are equally dark

d) all the above

21. Superposition of two light waves with same phase is known as ____________.

a) destructive interference

b) constructive interference

c) diffraction

d) refraction

22. In interference phenomena the intensity of light gets -------- at the region of

superposition of coherent light waves.

a)modified

b) remains the same

c) a&b


23. Two light waves are said to be coherent when they have ____________.

a) same frequency

b) zero phase difference or constant phase difference

c) emitted from two light sources

d) both (a) and (b)

24. When two waves are combined with each other then the resultant wave amplitude

depends on -----------of the two waves.

a) the relative phase

b) frequency

c) time


25.When two waves are combined with each other, then the resultant wave has ------

wavelength as that of the individual waves.

a) Same

b) different

c) less


26. When two closely spaced slits are illuminated with a monochromatic light the two slits

act as two coherent sources. The method of producing these sources is known as

____________.

a) division of amplitude

b) superposition

c) division of wavefront

d) division of intensity

27. When a monochromatic light is incident on two reflecting surfaces it produces two

coherent light waves. This method of producing coherent light waves is known as

____________.

a) division of wavefront

b) division of amplitude

c) division of intensity

d) superposition

28. The Young double slit experiment illustrates ____________.

a) interference of light waves

b) diffraction of light waves

c) polarization of light waves

d) refraction of light waves

29. Thomas Young explained the interference pattern produced in his experiment by

applying ____________.

a) Einstein theory of relativity

b) Newtons corpuscular theory of light

c) Huygens wave theory of light


30. when two waves are combined with each other then the amplitude of the resultant

wave will be increased if --------

a) the phase difference between them is equal to an integral multiples of the

, where is an integer.

b) the phase difference between them is equal to an odd multiples of the , where

is an integer.

c) the phase difference between them is equal to an odd multiples of the (2 + 1) ,

where is an integer.


31. Maximum intensity occurs in the interference pattern when the path difference between

the interfering light waves is equal to ____________.

a) half integer multiples of wavelength

b) constant multiples of wavelength

c) both (a) and (b)

d) integer multiples of wavelength

32. Minimum intensity occurs in the interference pattern when the path difference between

interfering light waves is equal to ____________.

a) half integer multiples of wavelength

b) integer multiples of wavelength

c) constant multiples of wave length

d) both (a) and (b)

33. The coherent light waves emitted by the coherent sources should maintain a -------or -

-----. Path difference between them.

a) Constant

b) zero

c) both a&b


34. When two waves are combined with each other then the amplitude of the resultant

wave will be minimum if --------

a) the phase difference between them is equal to an integral multiple of the ,

where is an integer.

b) the phase difference between them is equal to an odd multiple of the , where

is an integer.

c) the phase difference between them is equal to an odd multiple of the ( +

)/ , where is an integer.


35. Modification in the distribution of intensity in the region of superposition of two or more

coherent waves is known as ____________.

a) Refraction

b) Reflection

c) Diffraction

d) Interference

36. If one of the two slits of the Youngs double slit experiment is partially painted such that

it transmits half the intensity of the other ____________.

a) the darker fringes appear slightly brighter

b) the brighter fringes appear slightly darker

c) both (a) and (b)

d) there is no effect

37. Two light sources are said to be coherent, then emitted light waves from it must

have

a) same frequency

b) constant phase difference

c) same wavelength

d) all the above

38. In the case of constructive interference, the resultant amplitude is maximum if phase

difference between the superposition of waves is equal to

a) 2n

b) n

c) (2n-1)

d)None of the above

39. In case of destructive interference, the resultant amplitude is minimum if phase

difference between the superposition of waves is equal to

a) 2n

b) (2n-1)

c) n

d)None of the above

40. The resultant intensity due to the superposition of waves of constant phase difference is

a)I=2a2cos22 /2

b)I=4a2cos2/2

c)I=2a2sin2/2

d)I=4a2sin2/2

41. When two waves having amplitudes and are superposed at a region of space then

the resultant amplitude is

a) (a2+b2+2abcos)

b )(a2-b2+2abcos

c) (a2-b2-2abcos)

d)None of the above

42. When two waves are in phase with each other are superposed at a region of space,

then the resultant wave amplitude is equal to

a) Sum of the amplitudes of the individual waves

b) Difference of the amplitudes of the individual waves

c) Sum of the squares of the amplitude of individual waves


43. When two waves are out of phase with each other are superposed at a region of space,

then the resultant wave amplitude is equal to

a) Sum of the amplitudes of the individual waves

b) Difference in the amplitudes of the individual waves

c) Sum of the squares of the amplitude of individual waves


44. Which of the following statements are correct?

a). Coherent waves to be obtained by division of amplitude of the incident light on a

thin film

b) Coherent waves to be obtained by division of wavefront of the incident light on

two closely spaced slits.

c) a& b

d). None the above.

45 When a light is reflected from the surface of denser medium, then the reflected light

undergoes a phase change of

a)

b) No phase change

c)

2

d) None of above.

46 When a light is reflected from the surface of rarer medium, then the reflected light

undergoes

a)

b) No phase change

c)

2

d) None of above

47. When the light source emits light waves then such light waves should maintain a

constant phase within a time of -------.

a)

b) 106

c) a&b

d) None of the above.

48. To obtain a sustained interference pattern, the following condition should be satisfied.

a).Two light sources must be coherent and emits monochromatic light waves

b). Two light sources must be in-coherent and emits different light waves of different

wavelengths

c) a&b


49. When light waves are emitted by in-coherent light sources are superposed at region of

space, then the resultant intensity becomes

a) Sum of the intensities of the individual light waves

b) Difference in intensities of the individual light waves

c). a& b


50 when light waves are coming from two individual light sources are superposed then

a) Interference pattern to be observed at the superposition region

b) No interference pattern to be observed at the superposition region

c) Uniform illumination to be observed at the region of superposition

d) b&c

51. In Youngs double slit experiment, when d is the separation between the two coherent

sources, D the distance between the coherent sources and the screen and is the

wavelength of the light then

a)=d/D

b)=Dd/

c)= D/d

d)=d/d

52. In Youngs double slit experiment, the separation between the slits is halved and the

distance between the coherent sources and the screen is doubled .The fringe width is

equal to

a)halved

b)double

c)unchanged

d)tripled

53 In Youngs double slit experiment, the separation between the slits is and the

distance between the slits and screen is then the condition to get the stationary

interference pattern is

a)

b)

c) =


54 When a thin film of oil or soap bubble is illuminated with white light, multiple

colours appears one can view the reflected light from it .This is due to ------

phenomenon.

a) Diffraction

b) polarization

c) total internal reflection

d) interference

55. Interference phenomenon

a) Obeys the law of conservation of energy

b) Do not obeys the law of conservation of energy

c) there is a creation of energy at the superposition region


56 when a monochromatic light is incident on a thin film then the condition for

constructive interference is

a) =(+)

, = ,, ,., ,

b) =(2+1)

3, = 1,2,3, ..

c) =(1)

2, = 1,2,3. ,,

e) None of the above

57 when a monochromatic light is incident on a thin film then the condition for

destructive interference is

a) = , = ,, ., ,

b) b) =(2+1)

3, = 1,2,3, ..

c) c) =(1)

2, = 1,2,3. ,,


58. Brightness of the light wave depends on -----------

a) amplitude

b) frequency

c) wavelength


59. A double slit arrangement is illuminated first with red light then with blue light,

which one produces wider fringes than the other.

a) red

b) blue

c) both colours do not produce wider fringes


60. A double slit arrangement is illuminated first with red light then with blue light,

which one produces more number of fringes than the other.

a) red

b) blue

c) both colours do not produce wider fringes


61. When a monochromatic light of wavelength is incident on a thin film of thickness

whose refractive index is then the condition for constructive interference is

a) = ( + )/

b) 2 cos =

c) 2


62. When a monochromatic light of wavelength is incident on a thin film of thickness

whose refractive index is then the condition for destructive interference is

a) 2 cos = (2 + 1)/2

b) =

c) 2


63. When a monochromatic light of wavelength is normally incident on a thin film of

thickness whose refractive index is = 1 then the condition for constructive

interference is

a) = ( + )/

b) 2 cos =

c) 2


64. When a monochromatic light of wavelength is normally incident on a thin film of

thickness whose refractive index is = 1 then the condition for destructive

interference is

a) 2 = (2 + 1)/2

b) =

c) 2


65. When a monochromatic light of wavelength is normally incident on a magnesium

fluoride thin film of refractive index coated with a thickness on a lens, then what

is the minimum thickness to be coated as a thin film on a less is --------to minimize

the loss of light energy due to refection.

a) =

b) =

c) =

2


66. When a monochromatic light of wavelength is incident normally from air on a thin

film of refractive index deposited on a lens with a refractive index , then the

condition for destructive interference is

a) < <

b) < >

c) > <

d) = =

67. when an oil film of refractive index 1.50 is deposited as a thin film on the water with

refractive index 1.33, then a monochromatic light is incident from air of refractive

index 1 on the oil film the constructive interference will occur if the film thickness is

---------.

a) one-fourth of the wavelength of light in the oil

b) half of the wavelength of incident light

c) the wavelength of incident light

d) b& c

68. when an oil film of refractive index 1.50 is deposited as a thin film on the water with

refractive index 1.33, then a monochromatic light is incident from air of refractive

index 1 on the oil film the destructive interference will occur if the film thickness is -

--------.

a) one-fourth of the wavelength of incident light

b) half of the wavelength of light in the oil

c) the wavelength of incident light

d) b& c Note: [ =

]

69. In an antireflection coating on a camera lens , the amplitude condition is

a) =

b) =

c) =

d) None of above

70. Which of the following statement is true?

a) A thin film having zero thickness at one end and progressively increasing to a particular thickness at the other end is called a wedge shaped thin film. b) A thin film having uniform thickness is called as a wedge shaped thin film

c) A thin film having zigzag thickness is called as a wedge shaped thin film d) both b&c

71. Which of the following statement is true? a) A thin wedge of air film can be formed by two glasses slides on each other at one edge with a small angle and separated by a thin spacer at the opposite edge.

b) A thin wedge of air film can be formed by two glasses slides on each other at one edge with a large angle and separated by a thin spacer at the opposite edge. c) A thin wedge of air film can be formed by two glasses slides parallel one over the

other. d) b&c

72 What type of interference pattern can be observed in a wedge shaped air thin film? a) Parallel interference pattern

b) circular interference pattern c) not observed any interference pattern


73. The width of the interference fringe in a particular wedge shaped air thin film depends on ---------- . a) The thickness of the spacer and wavelength of the incident light on the thin film

b) The distance of the spacer from other end c) both a & b d) None of the above

74 Two glass plates of 10 cm long are touching on one side and are separated by 3 microns on the other. If the light of wavelength of 450nm is incident on this film , then at what thickness changes the dark bands occurs?

a) 0.225 microns

b) o.5 microns c) 1 micron d) b & c

75. In the case of wedge shaped air thin film , the condition for constructive interference to be satisfied when -------

a) =(+)

, = , , ,

b) 2 = , = 0,1,2,3

c) 2 =(+1)

2, = 0,1,2,3

d) b & c

76 In the case of wedge shaped air thin film , the condition for destructive interference to be satisfied when -------

a) 2 =(2+1)

2, = 0,1,2,3

b) = , = , , ,

c) 2 =(+1)

2, = 0,1,2,3

d) b & c

77. The following statement is true

a) A thin air film with increasing radius outward from the contact point of concave surface of plano- convex lens and the plane glass plate is called as a circular air thin film

b) A thin air film with decreasing radius outward from the contact point of convex surface of plano- convex lens and the plane glass plate is called as a circular air thin film

c) A thin air film of uniform thickness between the plano-convex lens and the plane glass plate is called as circular air thin film

d) b & c

78 When a circular air thin film is illuminated by a monochromatic light of wavelength

is viewed in the reflected system the -------------- interference pattern will be

observed.

a) Parallel

b) circular

c) curved


79. In Newtons rings experiment the coherent light waves can be obtained by -------------

-- method.

a) the division of wavefront

b) the division of amplitude

c) Both a & b


80 Why the centre of the Newtons rings is dark?

a) Path difference between the reflected waves from the centre of the circular air

thin film is equal to/ at which the thickness of the film is zero

b) Path difference between the reflected waves from the centre of the circular thin air

film is equal to at which the thickness of the film is zero

c) Path difference between the reflected waves from the centre of the circular thin air

film is equal to /4 at which the thickness of the film is zero.

d) b & c

81. The diameter of the dark rings is -------------

a) =

b) =

c) =


82. When the Newtons rings are viewed through a microscope, the central ring is seen

dark because

a) Phase difference of due to phase change on reflection

b Phase difference of /2 due to phase change on reflection

c) Path difference of due to phase change on reflection

d) Phase difference of 2 due to phase change on reflection

83 The air thin film in a Newtons ring apparatus is replaced by an oil film then the

radius of the rings

a) remains the same

b) increases

c) decreases


84 In Newtons rings experiment the diameter of dark ring is proportional to

a)n

b)(2n-1)

c)(2n-1)


85 In Newtons rings experiment the diameter of bright ring is proportional to

a)(n-1)

b)2n-1

c)(2n-1)

d)n

86 The air thin film in a Newtons ring apparatus is replaced by liquid film, and then the

refractive index of the liquid is

a) =(

)

(

)

b) =(

2 +2)

2 +

2

c) =(

2 2)

2 +

2

d)None of the above

87 A circular fringe pattern will be observed in Newtons rings interference and is due

to light rays reflected from -----------.

a) the lower surface of the plano-convex lens and upper surface of the glass plate

b) the lower surface of glass plate and upper surface of the plano-convex lens

c) the Lower surface of plano-convex lens and lower surface of glass plate

d)Upper surface of plano convex lens and upper surface of glass plate

88 when the light is reflected from the point at which the thickness of the circular air

thin film is = 0 then the interfering waves must have -----------------.

a) in phase with each other

b) out of phase with each other

c) No phase between them


89 Which of the following statement is true?

a) Each maximum or minimum is at a locus of constant film thickness since the

locus of all points having same thickness fall on a circular having its centre is at

the point of thickness = .

b) Each maximum or minimum is at a locus of constant film thickness since the locus

of all points having different thickness fall on a circular having its centre is at the

point of thickness = 0.

c) Each maximum or minimum is at a locus of constant film thickness since the locus

of all points having same thickness fall on a circular having its centre is at the point

of thickness 0.

d) b & c

90 When a drop of water is introduced between the glass plate and plano-convex lens in

Newtons rings system then the ring pattern

a) Contracts

b) expands

c) remains same

d) first expands then contracts

91 In Newtons rings experiment the radii of the and ( + 4) dark rings are

represents 5mm and 7mm . What is the value of m ?

a) 2

b) 4

c) 8

d) 10

92 The path difference between two monochromatic light waves of wavelengths 4000

is 2 107. The phase difference between them is

a)

b) 2

c) 3/2

d) /2

93. In Youngs double silt experiment the third bright band for wavelength of light

6000 is coincides with the fourth bright band for wavelength of light in the same

arrangement . The wavelength of the another source is

a)

b) 6000

c) 5000

d) 4000

94. Coherent light of wavelength 633nm from a He-Ne laser falls on a double slit with a

slit separation of 0.103mm. An interference pattern is produced on a screen 2.56mm

from the slits. Calculate the distance of the fourth order bright fringe from the central

image.

a) 6.29 cm

b) 8.5 cm

c) 10 cm

d) None of the above Note: [4 =4

]

95. Which of the following lights will produce an interference pattern with the largest separation between the bright fringes?

a) Red

b) green c) orange d) blue

96 A thin film of thickness 120nm has a refractive index of 1.35 . When viewed in the

reflected system form it, what wavelength of light is strongly reflected?

a) 4000

b)

c) 5000

d) 7000

97 A camera lens of refractive index 1.5 is coated with a film of magnesium fluoride of

refractive index 1.24. What should be the minimum thickness of the film to minimize

reflected light with wavelength of 450nm?

a) 90.7nm

b) 95 nm

c) 100nm

d) 96nm

98 A camera lens of refractive index 1.5 is coated with a film of magnesium fluoride of

refractive index 1.25. What should be the minimum thickness of the film to minimize

reflected light with wavelength of 550nm?

a) 110 nm

b) 95 nm

c) 100nm

d) 96nm

99 An air wedge between two plane glass plates each of which has 10.0 cm long and separated at one end by a paper of thickness of 0.082 mm, is illuminated with a blue light of wavelength 475 nm. What is the spacing of the dark fringes in the

interference pattern reflected from the air wedge? a) .

b) 3.9 102

c) 5 102


100 A thin transparent glass plate is placed in the light coming from the two slits then the

fringe width will be---------.

a) remains same

b) decreases

c) increases


101 When white light is incident on the two slits then the interference pattern consists of -

--------------.

a) white central fringe with dark fringes having different intensities

b) white central fringe with dark fringes having different intensities

c) dark central fringe with white fringes having different intensities


102.A measure of the correlation between the phases of light wave at different points over a

distance along the direction of propagation is known as ____________.

a) spatial coherence

b) interference distance

c) temporal coherence

d) none of these

103.The measure of the distance along the direction of wave propagation over which the

wave front remains in phase is known as ____________.

a) coherence length

b) special length

c) diffraction distance

d) interference distance

104.The relation between coherence length and the spectral line width is given by

a) =

b) =2

c) =3

d) =

105.When light ray suffers reflection at the interface between air and glass, the change of

phase of reflected wave is equal to ____________.

a) 0

b)

c) /2

d) 2

106.The optical path difference between the reflected rays from a thin film is given by the

formula ____________.

1) 2

2) 2

3) 2 cos +

4) 2 +

2

107.The reason for the appearance of colours on soap bubbles, oil films, heated metal

surfaces etc., is due to ____________.

a) Interference

b) Diffraction

c) Reflection

d) Refraction

108.The materials normally used for anti-reflection coatings on glass are _________.

a) Magnesium fluoride

b) Cryolite, Zinc sulphide

c) Sodium chloride

d) Both (a) and (b)

109.A wedge shape film is formed by introducing a wire of diameter d at one end of the pair

of glass plates of length L. When a light of wavelength l falls normally on wedge shaped

air film interference fringes are observed. The fringe width of the interference bands is

given by __________.

a) =

2

b) =

c) =

(a) None of the above

110.When the wedge shaped film is illuminated by white light coloured fringes are observed

due to ___________.

a) variation of wavelength

b) variation of thickness

c) Both (a) and (b)

d) refraction of light

111.In Newtons rings experiment the radii of dark rings are directly proportional to the

____________.

a) square root of odd numbers

b) natural numbers

c) square root of natural numbers

d) complex numbers

112.In Newtons rings experiment the radii of bright fringes are directly proportional to the

____________.

a) square root of odd numbers

b) natural numbers

c) square root of natural numbers

d) complex numbers

113.Newtons rings experiment can be used to determine _________.

a) Wavelength of light

b) Radius of curvature of the lens

c) Thickness of the air film

d) Both (a) and (b)

114.Newtons rings are formed due to the phenomenon of ________.

a) diffraction

b) reflection

c) interference

d) polarization

115.While grinding the lenses the manufacturers look for ________.

a) Smooth surface

b) Perfect Newtons rings

c) Perfect reflection from surfaces


Answers:

1)c 2)b 3)b 4)a 5)a 6)a 7)b 8)a 9)c 10)d

11)b 12)d 13)a 14)c 15)c 16)d 17)b 18)a 19) c 20)d

21)b 22)a 23)d 24)a 25)a 26)c 27)b 28)a 29)c 30)a

31)d 32)a 33)c 34)c 35)d 36) 37)d 38)a 39)b 40)b

41)a 42)a 43)b 44)c 45)a 46)b 47)a 48)a 49)a 50)d

51)c 52)c 53)a 54)d 55)a 56)a 57)a 58)a 59)a 60)b

61)a 62)b 63)a 64)b 65)a 66)a 67)a 68)b 69)a 70)a

71)a 72)a 73)a 74)a 75)a 76)b 77)a 78)b 79)b 80)a

81)a 82)a 83)c 84)a 85)c 86)a 87)a 88)b 89)a 90)a

91)d 92)a 93)a 94)a 95)a 96)b 97)a 98)a 99)a 100)a

101)a 102)c 103)b 104)b 105)b 106)d 107)a 108)a 109)b 110)c

111)a 112)c 113)d 114)c 115)b

1.2. Diffraction of light

1. Bending of light around the edges of an object or obstacle is called ________.

a) reflection

b) refraction

c) diffraction

d) interference

2. When a monochromatic light of wavelength is incident on a slit of width then the

condition for diffraction to occur is

a) b) c) >

2 d) None of the above

3. The phenomenon of diffraction was explained by Fresnel by applying _________.

a) The Huygens principle in conjunction with the principle of interference

b) Newtons corpuscular theory in conjunction with the principle of interference

c) The Huygens principle in conjunction with the rectilinear propagation of light

d) Einstein photoelectric effect

4. In Fresnel diffraction the source of light and screen are _________.

a) at finite distance from the diffracting object

b) at long distance from the diffracting body

c) at infinite distance from the diffracting body

d) at a suitable distance from the diffracting body

5. Fresnel diffraction is also called as

a) Near field diffraction

b) far-field diffraction

c) Both a & b

d) None of above

6. In Fraunhofer diffraction the source of light and screen are __________.

a) At finite distance from the diffracting body

b) At long distance from the diffracting body

c) Effectively at an infinite distance from the diffracting body

d) At a suitable distance from the diffracting body

7. Fraunhoffer diffraction is also called as

a) Near field diffraction

b) far-field diffraction

c) both a & b

d) None of above

8. When the source of light is at larger distance from the slit, then the incident light on

the silt is a ---------------.

a) Plane wavefront

b) spherical wavefront

c) cylindrical wavefront


9. A point light source emits a ------------.

a) Plane wavefront




10. A linear light source emits a -----------.

a) Plane wavefront




11. Diffraction is a

a) Particle phenomenon

b) wave phenomenon

c) both a & b


12. In the diffraction pattern the central maximum to be observed due to ------- of

secondary wavelets coming from the slits since they are in phase with one another.

a) Destructive interference

b) constructive interference

c) both a & b


13. In the diffraction pattern the central maximum is called as

a) First order

b) zero order

c) second order


14. The intensity of diffraction bands as we move away from the central band _______.

a) remains same throughout

b) increases gradually

c) increases and then decreases

d) decreases gradually

15. The diffraction pattern produced by two narrow slits separated by a small distance

consists of _________.

a) interference pattern produced by both the slits and the effective diffraction pattern

b) diffraction pattern produced by both the slits

c) Interference pattern produced by both the slits

d) Interference pattern produced by two slits and the diffraction pattern by a single

slit

16. The resultant intensity in the diffraction pattern produced by two silts is given by

a) =

b) = 02

2 2

c) = 302

2 2


17. In the resultant expression for intensity in the fraunhoffer diffraction at a double slit

the term 02

2 epresents

a)interference pattern

b)diffraction pattern due to single slit

c)both a&b

d)none

18. The phase difference between the secondary wavelets originating from the end points

of any two slits is

a) =

b) =(+) sin

c) = sin


19. The phase difference between the secondary wavelets originating from the two

effective points sources placed at the middle of the each silt of width and separated

by distance.

) = sin

b) =(+)

c) = sin


20. A diffraction pattern is obtained using a beam of red light. What happens if the red

light is replaced by blue light?

a) Bands disappears

b) No change in the diffraction pattern

c) diffraction pattern becomes narrower and crowded together

d) diffraction pattern becomes broader and farther apart

21. The intensity of the central maximum in the diffraction pattern produced by two silts

is------.

a)

b) 0

c) 30


22. In which class of diffraction the lenses are required.

a)Fresnels

b) Fraunhoffer

c) both a&b

d)None of the above

23. In a double slit diffraction the distance between slits is equal to the slit width. If n and m

represent the interference and diffraction orders respectively then the condition for

missing diffraction pattern is given by _________.

a) n=m

b) n=2m

c) n=3m

d) n=4m

24. In double slit diffraction, if the width of the slit is equal to the spacing of the opaque

region between the slits then

a) All interference maxima will be missing b) all interference maxima will be

present

c) Even order interference maxima will be missing

d) Diffraction fringes and interference fringes exactly coincide and hence totally

disappear

25. The diffraction pattern will be dominated by interference effects in the double slit

diffraction when---------.

a) is much larger than

b) is much smaller than

c) =


26. In double slit diffraction, the shape of the diffraction pattern depends on

a) Width of the slit b) the distance between two silts c) =

d) None of the above 27. In double slit diffraction, the shape of the interference pattern is determined by-----.

a) the distance between the slits

b) Width of the slit

c) =


28. In double slit diffraction, the diffraction pattern will be dominated by interference

effects when -----

a) is much larger than d

b) is much larger than e

c) =


29. In double slit diffraction, if -----------the two effects will contribute equally to the

fringe pattern

a) is much larger than d

b) is much larger than e

c) =


30. The intensity of the central maximum of double slit diffraction is ________ times the

intensity central maximum obtained in a single slit diffraction.

a) Two

b) Three

c) Five

d) Four

31. In the Fraunhofer diffraction, the number of slits is increased from two and then the

width of principal maxima ___________ .

a) decreases

b) remains same

c) increases

d) is doubled

32. In the Fraunhofer diffraction, the number of slits is increased from two and then the

sharpness and intensity of principal maxima _________.

a) decreases

b) remains same

c) increases

d) is doubled

33. One of the important uses of double slit diffraction experiment is the _____.

a) measurement of the wavelength of light.

b) measurement of annular diameter of stars.

c) measurement of distance between earth and moon.

d) measurement of fringe width.

34. In the resultant spectrum of the diffraction grating, all wavelength are present in the---

--------------.

a) First order spectrum

b) zero order maximum or central maximum

c) third order spectrum


35. In the resultant spectrum of the diffraction grating, the zero order maximum or central

maximum occurs when -----------------.

a) =

b) = 1

c) = 3


36. In the resultant spectrum of the diffraction grating, the first order maximum occurs

when -----------------.

a) = 0

b) =

c) = 3



a) The diffracting grating consists of a large number of equally spaced narrow

and parallel slits.

b) The diffracting grating consists of a large number of unequally spaced parallel slits c) In some regions of the diffracting grating have a large number of equally spaced

parallel slits and the other regions unequally spaced parallel slits d) None of the above

38. A -------- can be made by cutting parallel grooves on a glass plate since the spaces between the grooves are transparent to the light so it can act as separate slit and the

grooves act as opaque region. a) Plane Transmission grating

b) Reflection grating

c) Both a & b


39. The plane transmission grating consists of number of equally spaced parallel slits. The

width of one slit and one opaque space is called _______.

a) diffraction element

b) transmission element

c) interference element

d) grating element

40. The principal use of diffraction grating is to find the____________.

a) wavelengths of spectral lines of a given source.

b) intensity of spectral lines of a given source.

c) width of spectral lines of a given source.

d) none of the above.

41. A diffraction grating has number of slits of width with grating element ( + )

and then the resultant intensity is given by

a) = (

)

(

)

b) = 0 (sin

sin )

2

c) = 0 (sin

)

2


42. In a diffraction pattern produced by a grating, the intensity of principal maxima is

proportional to_________.

a) number of slits

b) square root of number of slits

c) cube of number of slits

d) square of number of slits

43. In the spectrum of diffraction grating which has number of slits of width with

grating element ( + ) , then the resultant intensity of the central maximum is

a)

b) 2

c) 3


44. The principal maxima can be seen ,in different order spectra of the diffraction grating

which has number of slits of width with grating element ( + ) ,when ------

condition should be satisfied.

a) ( + ) = , = , ,,

b) d sin = , = 0,1,2,

c) sin =


45. In the diffraction grating experiment, for a particular plane transmission grating, the

wavelength of the light source depends on --------- the angle of diffraction.

a)

b)

c)

d)

46. In the diffraction spectrum produced by the diffraction grating each spectral line in it

is a characteristic of the ---------------- present in the light source.

a) Wavelength

b) amplitude

c) Phase


47. Which spectral line has small angle of diffraction in the diffraction spectrum of the

white light source produced by the diffraction grating.

a) Red

b) blue

c) violate


48. Which spectral line has large angle of diffraction in the diffraction spectrum of white

light source produced by the diffraction grating.

a) Red

b) Blue

c) Violate


49. In the diffraction pattern produced by a grating having N number of slits, the number of

secondary minima between successive principal maxima is ______.

a) N-3

b) N-2

c) N-1

d) N

50. In the diffraction pattern produced by a grating, the intensity of principal maxima

_________ with increasing order.

a) increases

b) remains same

c) decreases


51. In the diffraction pattern produced by a grating, the grating spectra _________ with

increasing order.

a) are more dispersed

b) are not dispersed

c) are less dispersed

d) get closer

52. In the diffraction grating experiment the order of the diffraction spectra increases the

intensity of the each diffraction spectrum ---------- than the previous one.

a) Increases

b) Decreases

c) Will be same


53. The ability of an optical instrument to produce separate images of two objects is called

__________.

a) reflection power

b) magnification power

c) resolving power

d) refraction power

54. The limit of resolution of an optical instrument was proposed by ____________.

a) Newton

b) Rayleigh

c) Einstein

d) Galileo

55. The two objects are said to be resolved when____________.

a) the central maximum of one object falls on the central maximum of the second

b) the central maximum of one object falls on the first minimum of second object

c) the first minimum of one object falls on the central minimum of second object

d) Both (b) and (c)

56. The resolving power of a grating is defined as ____________.

a) the measure of its ability to separate two adjacent spectral lines

b) the measurement closeness of two spectral lines

c) the superposition of two spectral lines


57. The unit of resolving power is ____________.

a) joules

b) meters per sec

c) Kelvin per degree

d) Dimensionless

58. In the grating spectrum, the wavelengths of two adjacent spectral lines are 1and 2. The

resolving power of the grating is given by ____________.

a) 1+ 2

(1 2)

b) 1 2

(1+ 2)

c) 1+ 2

2(1 2)

d)

( )

59. The resolving power of a grating is ____________.

a) directly proportional to the number of lines on the grating

b) directly proportional to the order of the grating spectrum

c) inversely proportional to the number of lines on the grating

d) both (a) and (b)

60. Which of the following properties of light conclusively supports wave theory of light?

a)Interference and diffraction of light

b) photoelectric effect c) light obeys the law of reflection


Answers:

1)c 2)a 3)a 4)a 5)a 6)c 7)b 8)a 9)b 10)c

11)b 12)b 13)b 14)d 15)d 16)a 17)b 18)a 19) b 20)c

21)a 22)b 23)b 24)c 25)a 26)a 27)a 28)a 29)c 30)d

31)a 32)c 33)c 34)b 35)a 36)b 37)a 38)a 39)d 40)a

41)a 42)d 43)a 44)a 45)a 46)a 47)c 48)a 49)b 50)c

51)a 52)b 53)c 54)b 55)b 56)a 57)d 58)d 59)d 60)a

1.3. Polarization of light

1. The character of the motion of light wave can be understood by the---------------- of the light.

a) Polarization b) b) interference c) c) diffraction

d) d) None of the above

2. The polarization of a light wave is defined as the direction of ________.

a) electric vector

b) magnetic vector

c) propagation direction

d) both electric and magnetic vectors

3. Polarization of light proves that the light waves are ------------- in nature. a) Longitudinal b) transverse

c) spherical d) None of the above

4. Polarization of light means that a) the light wave acquires the property of one-sidedness.. b) the light wave does not acquire the property of one-sidedness.

c) the electric vector vibrates in a plane perpendicular to the direction of the propagation of the light.


5. The ordinary light wave means that

a) The electric vector vibrates in all possible planes perpendicular to the direction of the propagation of the light

b) The light wave exhibits symmetrical nature with respect to the direction of propagation

c) the light wave acquires the property of one-sidedness is called polarization of light

d) both a &b

6. Which of the following light wave exhibits asymmetric nature with respect to the direction of wave propagation? a) Un-polarized light wave

b) polarized light wave c) plane wave


7. The plane containing electric field vector and the direction of propagation is called

_________.

a) plane of propagation

b) plane of polarization

c) plane of vibration

d) plane of the electric field and magnetic field vector

8. The plane containing magnetic field vector and the direction of propagation is called

_________.

a) plane of propagation

b) plane of polarization

c) plane of vibration

d) plane of the electric field vector and magnetic field vector

9. When the plane of vibration of the electric vector is perpendicular with respect to the

direction of light propagation then such a polarized light is called as-----------. a) Linearly polarized light

b) plane polarized light c) a & b d) None of the above

10. The transverse nature of light is explained by the phenomenon of _________.

(a) interference

(b) diffraction

(c) refraction

(d) polarization

11. Circularly polarized light is produced when two plane polarized light waves of equal

amplitude are superposed with phase difference of __________.

a)

b)

c) (2+1)

2 ( n = integers)

d) Both (b) and (c)

12. Two plane polarized waves of equal amplitude are superimposed with a phase

difference of 5

2 . the light produced is ___________ polarized light.

a) elliptically

b) plane

c) right circularly

d) left circularly


difference of 3

2 . The light produced is ___________ polarized light.

a) elliptically

b) plane

c) right circularly

d) left circularly

14. What is the phase between the two plane polarized light for the formation of right

handed circularly polarized light?

a) It is equal to even multiple of

b) It is equal to odd multiple of

2

c) It is equal to even multiple of 3

2


15. What is the phase between the two plane polarized light for the formation of left

handed circularly polarized light?


2


a) It is equal to even multiple of 3

2


16. If the direction of vibration of electric vector starts from left to right when the circularly polarized light is propagating along the direction of z-axis then such a

circular polarized light is called as ----------. a) left circularly polarized light or clock-wise circularly polarized light

b) right circularly polarized light or clock-wise circularly polarized light c) plane polarized light d) None of the above

17. If the direction of vibration of electric vector starts from right to left when the

circularly polarized light is propagating along the direction of z-axis then such a circular polarized light is called as ----------. a) left circularly polarized light or clock-wise circularly polarized light

b) right circularly polarized light or clock-wise circularly polarized light c) plane polarized light


18. Any change in the amplitude of the circularly polarized light will be observed with

time while it is propagating along the direction of z-axis. b) Yes

c) no d) Both a & b e) None of the above

19. Elliptically polarized light is produced when two plane polarized light waves of unequal

amplitude are superposed with phase difference of __________.

(a)

(b)

2

(c) (2+1)

2

(d) Both (b) and (c)

20. If the direction of vibration of electric vector starts from left to right when the elliptically polarized light is propagating along the direction of z-axis then such a

elliptically polarized light is called as ----------.

a) Left- handed elliptically polarized light or clock-wise circularly polarized light

b) right handed circularly polarized light or clock-wise circularly polarized light c) plane polarized light


21. If the direction of vibration of electric vector starts from right to left when the

elliptically polarized light is propagating along the direction of z-axis then such a elliptically polarized light is called as ----------.

a) Left- handed elliptically polarized light or clock-wise circularly polarized light b) right handed circularly polarized light or anti clock-wise circularly

polarized light

c) plane polarized light d) None of the above

22. What is the phase between the two plane polarized light for the formation of left

handed elliptically polarized light?


2


f) It is equal to even multiple of 3

2

g) None of the above

23. Two plane polarized waves of unequal amplitude are superimposed with a phase

difference of 5

2 . the light produced is ___________ polarized light.

a) circularly

b) plane

c) right elliptically

d) left elliptically


difference of 3

2 . The light produced is ___________ polarized light.

a) circularly

b) plane

c) right elliptically

d) left elliptically

25. What is the phase between the two plane polarized light for the formation of right

handed elliptically polarized light?


b) It is equal to odd multiple of c) It is equal to even multiple of 2

None of the above

26. Any change in the amplitude of the elliptically polarized light will be observed with

time while it is propagating along the direction of z-axis. a) Yes

b) no c) both a & b


27. Which of the following statement is true? a) Any axis passing through the blunt corner of the anisotropic crystal or

birefringence crystal such that the three surfaces of the unit cell of it make

equal angles with that axis is called an optic axis.

b) Any axis passing through the blunt corner of the isotropic crystal such that the

three surfaces of the unit cell of it make equal angles with that axis is called an

optic axis.

c) Any axis do not pass through the blunt corner of the anisotropic crystal or

birefringence crystal such that the three surfaces of the unit cell of it make equal

angles with that axis is called an optic axis.



a) A plane passing through the blunt corners and perpendicular to the pair of parallel faces of the unit cell of the anisotropic crystal gives the principal

plane of that crystal.

b) A plane passing through the blunt corners and perpendicular to the pair of parallel faces of the unit cell of the isotropic crystals gives the principal plane of that

crystal. c) A plane does not pass through the blunt corners and perpendicular to the pair of

parallel faces of the anisotropic crystals gives the principal plane of that crystal.


29. Which of the following statement is true? a) When an un-polarized light is propagating along the optic axis of an anisotropic

crystal it does split into two polarized light i.e., double refraction

b) When an un-polarized light is propagating along the optic axis of an anisotropic crystal it does not split into two polarized light i.e., no double

refraction. c) When an un-polarized light is propagating along the optic axis of an isotropic

crystal it does not split into two polarized light.


30. When an un-polarized light is propagating perpendicular to the optic axis of an anisotropic crystal ----------------- can be observed. a) double refraction

b) no double refraction c) reflection


31. Light is reflected from a transparent surface. Reflected light is plane polarized when

_____.

a) the angle between reflected and refracted light is less than 90

b) the angle between reflected and refracted light is equal to

c) the angle between reflected and refracted light is greater than 90

d) the angle between reflected and refracted light is equal to 60

32. Production of plane polarized light by reflection was discovered by _________.

a) Thomas Young

b) Nicol

c) Mauls

d) Fraunhofer

33. Polarization of light by reflection depends on the angle of incidence. The incident angle

at which the maximum polarization occurs is known as ________.

a) angle of polarization

b) Brewster angle

c) angle of maximum incidence

d) both (a) and (b)

34. The tangent of the polarization angle is numerically equal to the refractive index of the

material. This law is known as ________.

a) Brewsters law

b) Malus law

c) Law of polarization

d) Newtons law

35. The refractive index for glass air interface is 1.5 and the angle of polarisation of reflected

light is ________.

a) 78

b)

c) 57

d) 55

36. The phenomenon of double refraction in calcite crystal was found by________.

a) Brewster

b) Thomas young

c) Erasmus Bertholinus

d) Paul M Dirac

37. The crystal structure of Iceland spar or calcite is rhombohedra. Each face of

rhombohedra is parallelogram having angles about ________.

a) 87 and 102

b) and

c) 105 and 58

d) 78 and 119

38. An incident ray falls normally on the face of the calcite crystal. The light ray splits into O-

ray and E-ray.

a) The O-ray refracts in the same direction of incident ray

b) The E-ray refracts in the same direction of incident ray

c) The O-ray refracts in a different path of incident ray

d) The angle of refraction is zero for E-ray

39. An incident ray falls normally on the face of the calcite crystal. The light ray splits into O-

ray and E-ray.

a) The O-ray refracts in a different path of incident ray

b) The E-ray refracts in a different path of incident ray

c) The E-ray refracts in the same direction of incident ray

d) The angle of refraction is zero for E-ray

40. In a double refraction of light through a quartz crystal the plane polarisation directions of

E-ray and O-ray are _________.

a) parallel to each other

b) lies at an angle of 45.50

c) perpendicular to each other

d) lies at angle of 450

41. In a calcite crystal the crystal axis is _________.

a) the line passing through opposite faces of the crystal

b) the line passing through the blunt corners of the crystal

c) the line passing through the opposite corners of the crystal

d) the line passing through the centre of the crystal

42. The optic axis of a quartz crystal is ___________.

(a) the line passing through the parallel faces of the crystal

(b) the line passing through the hexagonal axis of the crystal

(c) the line passing through the corners of the hexagonal structure

(d) the line passing through the blunt corners of the crystal

43. The principal plane of a calcite crystal is ___________.

a) Plane perpendicular to two opposite faces and contains optic axis of the crystal

b) Plane passing through the blunt corners of the crystal

c) The plane parallel to the two opposite faces of the crystal


44. The number of principal planes in a calcite crystal is equal to ______.

a) 4

b) 6

c) 5

d) 3

45. In a calcite crystal the principal plane cuts the crystal surfaces in a parallelogram having

angles ________.

a) 1020and 780

b) 1020and 63.50

c) and

d) 710and 1020

46. In negative uniaxial crystals the velocity of E-ray is _________ the direction of optic axis.

a) maximum at right angles to

b) minimum at right angles to

c) same as the velocity of O-ray at right angles to

d) maximum along

47. In negative uniaxial crystals the velocity of O-ray is _________ the direction of optic axis.

a) maximum along

b) minimum along

c) same as the velocity of O-ray in

d) same in all directions

48. In positive uniaxial crystals the velocity of E-ray is _________ the direction of optic axis.

a) maximum at right angles to

b) minimum at right angles to

c) same as the velocity of O-ray along

d) maximum along

49. In positive uniaxial crystals the ------ velocity of O-ray is perpendicular to the direction of

optic axis.

a) maximum

b) minimum

c) same as the velocity of E-ray

d) same in all directions

50. Nicol prism is used to produce ________.

a) plane polarized light

b) circularly polarized light

c) elliptically polarized light

d) unpolarized light

51. The two cut crystals in a Nicol prism are cemented with a material called ______.

a) transparent gum

b) Fevicol

c) Canada balsam

d) Sodium nitrate

52. In the Nicol prism the O-ray is eliminated using the phenomenon of ___________.

a) reflection

b) total internal reflection

c) refraction

d) absorption

53. The refractive index of Canada balsam is equal to________.

a) 1.658

b) 1.486

c) 1.33

d) 1.55

54. In a Nicol prism is used as a ________.

a) polarizer

b) analyzer

c) both (a) and (b)


55. In a Nicol prism the refractive index of O-ray is _________ the refractive index of E-ray.

a) greater than

b) less than

c) equal to


56. The nicol prism acts as a polarizing devise only when the angle of incidence of the

unpolarized light ray is _______.

a) about 250

b) about

c) about 350

d) about 450

57. A quarter wave plate introduces a phase difference of ______ between O-ray and E-ray.

a)

b) 3

2

c)

d) 5

2

58. A quarter wave plate introduces a path difference of ______ between O-ray and E-ray.

a) 2

b)

2

c)

d) 3

2

59. The thickness of a quarter wave plate made up of calcite crystal is given by________.

a) 2

( )

b)

4()

c)

( )

d)

4( )

60. The thickness of a quarter wave plate made up of quartz crystal is given by________.

a)

4()

b)

()

c)

2()

d) 2

( )

61. The thickness of the quarter wave plate made up of calcite crystal is _______. Given the

refractive indices = 1.6284 and = 1.4864. Take wave length of light = 5893 .

a) 80.85

b) .

c) 70.75

d) 75.75

62. A quarter wave plate is used to convert _________.

a) circularly polarized light into plane polarized light

b) elliptically polarized light into plane polarized light

c) plane polarized light into circularly polarized light

d) plane polarized light into elliptically polarized light

63. A half wave plate introduces a phase difference of ______ between O-ray and E-ray.

a)

2

b) 3

2

c)

d) 5

2

64. A half wave plate introduces a path difference of ______ between O-ray and E-ray.

a) 2

b)

c)

4

d) 3

2

65. The thickness of a quarter wave plate made up of calcite crystal is given by________.

a)

( )

b)

4()

c)

4( )

d)

( )

66. The thickness of a quarter wave plate made up of quartz crystal is given by________.

a)

4()

b)

( )

c)

()

d) 2

( )

67. A half wave plate is used to convert _________.

(a) left circularly polarized light into right circularly polarized light

(b) right circularly polarized light into left circularly polarized light

(c) plane polarized light into circularly polarized light

(d) both (a) and (b)

Answers

1)a 2)a 3)b 4)a 5)d 6)b 7)c 8)b 9)c 10)d

11)b 12)d 13)d 14)a 15)b 16)a 17)b 18)c 19) b 20)a

21)b 22)b 23)d 24)d 25)a 26)a 27)a 28)a 29)b 30)a

31)b 32)c 33)b 34)a 35)b 36)d 37)b 38)a 39)b 40)c

41)b 42)d 43)a 44)d 45)c 46)a 47)d 48)c 49)a 50)a

51)c 52)b 53)d 54)c 55)a 56)b 57)a 58)c 59)c 60)b

61)b 62)c 63)c 64)b 65)a 66)c 67)d

physical optics for instruments important bits

Documents

light waves

wavelength of light

c polarization of light

refraction of light

velocity of light c

properties of light

b particle

b greater