Chapter # 9 Nature of Light

PHYSICS

CHAPTER # 09 Physical Optics

1. 2. 3.

4. 5.

6.

7. 8. 9. 10. 11. 12. 13. 14. 15. 17.

Interference and diffraction support the: a) Quantum nature of light b) Complex nature of light c) Wave nature of light d) Transverse nature of light Velocity of light in vacuum is: a) Zero b) 3  105 Km sec-1 8 -1 c) 3  10 Km sec d) Infinite In a plane polarized light: a) Vibrations take place in all directions b) Vibrations take place in two perpendicular directions c) No vibrations at all d) Vibrations take place in one plane perpendicular to the directions of propagation of light In Newton’s rings seen through the reflected light: a) The central spot is bright b) The central spot is dark c) Both of the above d) None of these In Young’s double slit experiment D is the distance between slits and the screen d is the slit separation and  is the wave length of light used, then the fringe spacing is given by: D d d a) b) D d Dd c) D d)  In Young’s double slit experiment if the distance between the slits and also the distance between the slits and the screen is doubled, the fringe width is: a) Doubled b) Four times c) Half d) The same In Young’s double slit experiment using white light: a) Coloured fringes will be obtained b) Alternate dark and bright light will be seen c) No interference fringes will be seen d) None of these The appearance of colours in thin soap or oil film results from: a) Dispersion b) Refraction c) Reflection d) Interference The danger signals are red while eye is more sensitive to yellow because: a) Scattering in red is less than in yellow b) Scattering in yellow is less than that of red c) Red light is longer in wavelength than yellow d) None of these Light reaches the earth from sun in nearly: a) 16 minutes b) 10 minutes c) 8 minutes – 30 sec d) 8 sec Newton propounded his corpuscular theory on the basis of: a) Newton’s rings b) Rectilinear property of light c) Dispersion of white light d) Polarisation A point source of light situated in a homogenous medium gives rise to: a) A spherical wave front b) A plane wave front c) A cylindrical wave front d) An elliptical wave front Electromagnetic wave transport: a) Energy only b) Momentum only c) Both momentum and energy d) Momentum end disturbance The electromagnetic wave theory was proposed by: a) Hertz b) Young c) Huygen d) Maxwell Which of the following proves that light waves are transverse in nature? a) Polarisation b) Diffraction c) Interference d) Refraction The wave nature of light was proposed by: a) Newton b) Fresnel c) Maxwell d) Huygen

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C B D

B A

D

B D A C B A C D A D

PHYSICS

CHAPTER # 09 Physical Optics

18.

19. wave 20. 21. 22.

23. 24. 25. 26. 27. 28. 29. 30. 31. 32.

33. 34.

36.

The interference fringe spacing depends on: D a) The wavelength of light used b) The distance of screen from the coherent sources c) Separation between the sources d) All of the above In 1873, Maxwell showed that light was a form of: A a) High frequency electromagnetic wave b) Low frequency electromagnetic wave c) moderate wavelength electromagnetic wave d) Long wavelength electromagnetic Which one of the following properties of light does not change with the nature of the medium? a) Velocity b) Wavelength c) Amplitude d) Frequency What vibrates when electromagnetic waves travel through vacuum? a) Magnetic field b) Electric field c) Electric and magnetic field d) Gravitational field The condition for constructive interference in case of diffraction grating is: a) sin  = dm  b) 2d sin  = m    c) d sin = m d) d sin  = 2m  According to modern idea about the nature of light, light shows: a) Particle nature only b) Wave nature only c) Dual nature d) Electromagnetic wave nature The speed of light in vacuum depends upon: a) Time period b) Frequency c) Wavelength d) None of these When light enters glass (or any other medium) it suffers a change in: a) Wavelength only b) Frequency only c) Velocity only d) Both velocity and wavelength Photo-electric effect can be explained if light is considered to have: a) Wave nature b) Particle nature c) Dual nature d) None of these According to Einstein, light travels from one place to another in the form of: a) Waves b) Particles c) Photons d) Radiations In photo-electric effect, the energy of ejected electrons depend on: a) The intensity of light b) The frequency of light c) Both intensity and frequency d) amplitude of the above Longitudinal waves do not exhibit (show): a) Reflection b) Refraction c) Diffraction d) Polarisation The locus of all points in a medium having the same phase of vibration is called: a) Crest b) Trough c) Wavelength d) Wave front At a very large distance from a point source we get: a) An elliptical wave front b) A cylindrical wave front c) A plane wave front d) A rectangular wave front Huygen’s principle states that: a) Light travels in straight line b) Light travels in electromagnetic waves c) All points on primary wave front are source of secondary wavelets d) Light has dual nature In order to get the interference of light waves: a) The sources should be monochromatic b) The sources should be phase coherent c) The linear supper-position should be applicable d) All of these In Young’s double slit experiment, the condition for constructive interference (or bright fringes) is: a) d sin  = (m + ½ )  b) d sin  = m  c) d sin  = (m - ½ )  d) 2d sin  = m  The velocity of light was determined accurately by: a) Newton b) Michelson c) Huygen d) Young

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D C C

C D D B C B D B C C

D B

B

PHYSICS

CHAPTER # 09 Physical Optics

37.

38.

39. 40. 41. 42. 43. 44. 45. 46. 47.

48.

49.

The condition for constructive interference of two coherent beams is that the path difference should be: a) Integral multiple of  /2 b) Integral multiple of   c) Odd integral multiple of /2 d) Even integral multiple of  The condition for destructive interference of two coherent waves is that the path difference should be: a) Integral multiple of  /2 b) Integral multiple of  c) Odd integral multiple of  /2 d) Even integral multiple of  /2 Soap film in sunlight appears coloured due to: a) Dispersion of light b) Diffraction of light c) Scattering of light d) Interference of light IN an interference pattern: a) Bright fringes are wider than dark fringes b) Dark fringes are wider than bright fringes c) Both dark and bright fringes are of equal width d) Central fringes are brighter than the outer A thin layer of oil on the surface of water looks coloured due to: a) Polarisation of light b) Different elements present in the oil c) Interference of light d) The transmission of light The bending of a beam of light when it passes from one medium to another is known as: a) Refraction b) Reflection c) Diffraction d) Dispersion The appearance of colous in thin films is due to: a) Diffraction b) Reflection c) Interference d) Polarisation Newton’s rings are formed due to: a) Diffraction of light b) Interference of light c) Polarisation of light d) Reflection of light The wavelength of X-rays is of the order of: a) 10 A0 b) 1000 A0 0 c) 1 A d) 100 A0 Polarisation of light shows that light is: a) Corpuscular in nature b) Of extremely short waves c) Longitudinal waves d) Transverse waves The energy of a photon ‘E’ is proportional to:   a) The magnetic field H b) The electric field E   c) Both the electric and magnetic fields H and E d) Frequency f The path differnce ‘d’ for constructive interference should be: a) d =  /2 b) d = 3  /2  c) d = 5 /2 d) d = m  The energy of a photon is represented by: hf a)

50. 51. 52. 53. 54.

c2

h T c) Huygen’s principle is used to: a) Find index of refraction c) Locate the wave front The index of refraction of a medium depends on: a) Frequency of light c) Nature of the medium The complementary colour of yellow is: a) Blue c) Red Electromagnetic waves are produced by: a) Accelerated bodies c) Charges at rest or in uniform motion Energy of a photon of violet colour is: a) Greater than that of red colour c) The same as that of red colour

Bahadur Ali Qureshi

B

C

D C C A C B C D D

D

C

b) hc2 h d)

c2 C

b) Explain polarisation d) Determine the speed of light C b) Wavelength of light d) Temperature A b) Green d) Orange D b) Heating a conductor d) Accelerated charges A b) Less than that of red colour d) None of these

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PHYSICS

CHAPTER # 09 Physical Optics

56.

The concept of corpuscular nature of light was given by: B a) Maxwell b) Newton c) Huygen d) Thomas Young 57. The wave nature of light was verified by: A a) Thomas Young b) Huygen c) Newton d) Maxwell 59. Which of the following properties proves that light behaves as particles? B I. Polarization II. Photo electric effect III. Compton effect IV. Diffraction a) I and II are correct b) II and III are correct c) III and IV are correct d) I and IV are correct 60. Which of the following properties of light does not depend upon the nature of the medium? D a) Velocity b) Wavelength c) Amplitude d) Frequency 61. To observe interference of light (between) the two waves must: D I. Be monochromatic II. Be phase coherent III. Obey the principle of linear superposition a) I and II are correct only b) II and III correct only c) I and III are correct only d) I, II and III are correct 62. Which of the following is nearly monochromatic? C a) Light from candle b) Light from simple lamp c) Light from sodium lamp d) Light from sun 63. In Young’s double slit experiment, the distance between two consecutive bright or dark fringes is: B   a) d / L b) L / d c) d / L  d) L /  d 64. In Young’s double slit experiment, if d is the separation between slits, L is the distance of screen from C the slits, then the position of m-th bright fringe ym will be: a) (m+1/2) L  / d, where m=0,1,2,3,… b) (m-1/2) L  / d, where m=0,1,2,3,… c) m(L  / d), where m=0,1,2,3,… d) (m+1/2) d / L  , where m=0,1,2,3,… 65. In Young’s double slit experiment, if we use white light then: D a) Coloured fringes will be observed b) Bright fringes will be observed c) Alternate dark and bright fringe will be observed d) No interference fringes will be seen 66. In Young’s double slit experiment, if the distance between slits and screen is halved the separation D between the slits doubled, then the fringe spacing will be: a) Doubled b) Halved c) Four times d) One fourth 67. In Young’s double slit experiment, the condition for destructive interference is: B     a) d sin = m if m=0,1,2,3,… b) d sin = (m+1/2) if m=0,1,2,3,… c) d sin  = (m-1/2)  if m=0,1,2,3,… d) d sin  = m/  68. Young’s double slit experiment can be used to determine: D a) Wavelength of monochromatic light b) Distance between the slits c) Fringe spacing d) All of these 69. Polaroids can be used: D a) To control head light glare in night driving b) To determine the concentration of optically active substance c) In curtain less window to adjust the amount of light d) All of them 70. Which one of the following is correct relation for Bragg’s law: B a) d sin  = m  b) d sin  = m  /2 c) d sin  = 2m  d) d sin  = m+  /2 71. In monochromatic red light a blue book will appear: C a) Blue b) Red c) Black d) Purple 72. Which one of the following properties is not found in both sound and light: C a) Interference b) Diffraction c) Polarization d) Reflection 73. Which one of the following cannot measure wavelength of X-rays in anyway: B a) Bragg’s law b) Diffraction grating c) Compton effect d) Photo electric effect

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PHYSICS

CHAPTER # 09 Physical Optics

74.

Which one of the following is used to measure the wavelength of X-rays? a) Young’s double slit experiment b) Diffraction grating c) Bragg’s law d) Photoelectric effect 75. In order to observe two successive bright or dark fringes in Michelson’s interferometer, the movable mirror is displaced through a distance of: a)  b)  / 2 c)  / 4 d) 2  76. In Michelson’s interferometer if the movable mirror is displaced through a distance of 0.05mm, 200 fringes are observed. The wavelength of light used in that case is: a) 5000 Ao b) 500 Ao o c) 50 A d) 5 Ao 77. In Michelson’s interferometer, if movable mirror is displaced through a distance equal to wavelength of monochromatic light then the number of bright fringes observed will be: a) 1 b) 2 c) 3 d) 4 78. Michelson’s interferometer is usually used to determine: a) Wavelength of light b) Velocity of light c) Amplitude of light d) Dispersion of light 79. For all practical purposes we consider that light travels in _______: a) Curved lines b) straight lines c) Sometimes curved and sometimes in straight line d) None of these 80. When light traveling in one medium strikes the boundary of another medium a part of it is sent back in the same medium, this is known as _______: a) Reflection b) Rarefraction c) Polarization d) Interference 82. The gradual change of light, by which we receive light at dawn or after sunset, is due to _______: a) Specular refraction b) Regular refraction c) Irregular refraction d) None of these 83. The image of a real object formed in a plane mirror is found to be _______: a) Real b) Virtual c) Curved d) None of these 84. An image that can be shown on the screen is called _______: a) Real b) Virtual c) Inverted d) Erect 85. If “Path difference” between two sounds is an integral multiple of wavelength, then _______ occurs: a) Constructive interference b) Destructive interference c) Different frequency range d) None of these 86. The velocity of a satellite or a star is determined by the change in frequency of signal (radio wave or light) they emit this phenomena is called _______: a) Shift theorem b) Dppler’s shift c) Polarization d) None of these 87. The wave having a discrete set of frequencies only can be set up to a medium. It is called _______: a) Quantization of frequency b) Resonance c) Photo-electric effect d) None of these 88. A spring 4m long resonates in Four segments (nodes at both ends). The frequency of the system is 20 Hz, then speed of the wave in the spring is _______: a) 40 m/sec b) 40 cm/sec c) 80 m/sec d) 100 m/sec 90. Newton’s rings illustrated the phenomenon of _______: a) Interference b) Diffraction c) Polarization d) Rarefraction 91. When light is incident on a diffraction grating, the light that will be deviated from central image will be _______: a) Yellow b) Violet c) Indigo d) Red 92. Rising and setting sun appears to be reddish because _______: a) Diffraction sends red rays to the earth at these times b) Scattering due to dust particles and air molecules is responsible for this effect c) Refraction is responsible for this effect d) Polarization is responsible for this effect

Bahadur Ali Qureshi

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C B

A

B

A B A

C B A A B

A A

A D

B

PHYSICS

CHAPTER # 09 Physical Optics

93. 94. 95.

96. 98.

99.

101. 102. 103. 104. 105. 106. 107.

108. 110. 111. 112.

Plane polarized light can be produced by _______: a) Simple reflection b) Double refraction c) Scattering of light d) All of these Which phenomenon do not cause the polarization of light _______: a) Reflection b) Interference c) Double refraction d) Scattering of light Polarization of light conclusively proves that _______: a) Light waves are longitudinal b) Light waves are transverse c) Light waves are not transverse d) Light waves are longitudinal as well as transverse The properties of light are explained by _______: a) Wave theory b) Particle theory c) Both wave and particle theories d) None of these Huygen’s concept of secondary waves _______: a) Allows us to find the focal length of thick lens b) Gives us the magnifying power of microscope c) Is a geometrical method to find the position of a wave front d) Is used to determine the velocity of light Light traveling from vacuum enters water, which of the following characteristics of light will remain unchanged? a) Velocity b) Amplitude c) Frequency d) Wavelength The waves that require a certain medium for their propagation are called _______: a) Mechanical waves b) Electromagnetic c) Matter waves d) None of these The bending of light around the edges of an object is called _______: a) Interference b) Polarization c) Diffraction d) Reflection The experimental evidence for occurrence of the diffraction of light was discovered by _______: a) Chistian Huygens b) Francesco Gimaldi c) Thomas Young d) Augustian Fresnel Refraction and reflection phenomena can be explained if light is considered to travel as _______: a) Wave b) Particle c) Both wave and particle d) None of these Photoelectric effect can be explained if light is considered to travel as _______: a) Wave b) Particle c) Both wave and particle d) None of these Electromagnetic waves transport _______: a) Energy and momentum b) Energy c) Momentum d) None of these Huygen’s principle is used to show that _______: a) Light travels in straight line b) Light has dual nature c) all points on primary wave front are source of secondary wavelet d) None of these To obtain interference of light the condition which must met is that source must be _______: a) Phase coherence b) Monochromatic c) Both phase coherence and monochromatic d) None of these In photoelectric effect, K.E. of an ejected electron depends upon _______ of light: a) Intensity b) Frequency c) Wavelength d) None of these According to quantum theory, the energy of a photon is directly proportional to _______ of light: a) Frequency b) Intensity c) Amplitude d) None of these In Michelson interferometer, wavelength of light is given by expression _______: a) P = m  b) P = 2 m  1 c) P = 2 m  d) None of these

Bahadur Ali Qureshi

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D A B

C C

C

B C B C C A C

C B A C

PHYSICS

CHAPTER # 09 Physical Optics

113. 114. 115.

The new position of a wave front time t is determined by using _______: a) Huygen’s principle b) Michelson interferometer c) Young’s double slit experiment d) Bragg’s formula X-rays were discovered by _______: a) W. Roentgen b) DeBroglie c) Young d) Michelson The splitting up of a beam of white light into its different colours is known as _______: a) Refraction b) Reflection c) Interference d) Dispersion

Bahadur Ali Qureshi

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A A D