InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Visible radiation has wavelengthA. `lambda gt 8000 Å`B. `lambda = 1` millimeterC. `lambda = 4000 Å` to 8000 ÅD. `lambda lt 4000 Å` |
| Answer» Correct Answer - C | |
| 52. |
The frequency of visible range spectrum is of the order ofA. `8 xx 10^(10) Hz`B. `5 xx 10^(14) Hz`C. `3 xx 10^(16) Hz`D. `5 xx 10^(3) Hz` |
| Answer» Correct Answer - B | |
| 53. |
The angle made by incident ray of light with the reflecting surface is calledA. angle of incidenceB. angle of reflectionC. angle of refractionD. glancing angle |
| Answer» Correct Answer - D | |
| 54. |
The angle made by incident ray of light with the reflecting surface is calledA. angle of incidenceB. angle of reflectionC. angle of refractionD. angle of emergence |
| Answer» Correct Answer - A | |
| 55. |
The angle of deviation is the angle between theA. incident ray and refracted raysB. incident ray and the normalC. refracted ray and the normalD. incident and emergent ray |
| Answer» Correct Answer - D | |
| 56. |
The laws of reflection of light are valid forA. plane mirror onlyB. concave mirrors onlyC. convex mirror onlyD. all reflecting surfaces only |
| Answer» Correct Answer - D | |
| 57. |
Which of the following statement is true in case of reflection of light ?A. Angle of incidence = Angle of reflectionB. Incident ray, reflected ray and normal lie in same planeC. Incident ray and reflected ray lie on opposite side of normalD. All of these |
| Answer» Correct Answer - C | |
| 58. |
A ray of light of wavelength `lambda` is incident on mirror at an angle of incidence `60^(@)`. The wavelength of light after reflection will beA. `2 lambda`B. `3 lambda`C. `lambda//2`D. `lambda` |
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Answer» Correct Answer - D Due to reflection there is no change in wavelength, velocity and frequency. |
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| 59. |
If a star is moving towards the earth, then the lines are shifted towardsA. redB. infraredC. blueD. green |
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Answer» Correct Answer - C When the source and observer approach each other, apparent frequency increases and hence wavelength decreases. This shift is called blue shift. |
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| 60. |
The twinkling of star is due toA. periodic bursts of light from the starB. interference between light from the sun and starC. partial absorption of light in the atmosphereD. refractive index fluctuation in the atmospheric |
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Answer» Correct Answer - D Due to refraction of light in atmosphere there is fluctuation in the refractive index, due to that, the star twinkles. |
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| 61. |
At noon, the overhead sun is of normal size. It is due toA. reflection of lightB. interference of lightC. polarisation of lightD. normal incidence of light through atmosphere for which angle of refraction is zero |
| Answer» Correct Answer - D | |
| 62. |
Who discovered a synthetic crystalline material iodosulphate of quinine ?A. W.H. HerapathB. P.H. LandC. W. NicolD. W. H. Brewster |
| Answer» Correct Answer - A | |
| 63. |
H-polarised is made ofA. nitro celluloseB. polyvinyl alcoholC. teflonD. polyvinyl chloride |
| Answer» Correct Answer - B | |
| 64. |
Signals of danger are made red, becauseA. our eye is most sensitive for red colourB. scattering is minimum for red colourC. scattering is maximum for red colourD. red colour is internationally accepted colour for danger |
| Answer» Correct Answer - B | |
| 65. |
An unpolarizing beam of light is incident on a group of four palarizing sheets, which are arranaged in such a way that the characteristic direction of each polarizing sheet makes an angle of `30^(@)` with that of the preceding sheet. What fraction of incident unpolarized light is transmitted ?A. 27/54B. 27/81C. 27/128D. 27/112 |
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Answer» Correct Answer - C Intensity of light transmitted by first polariser `= I_(1) = (I_(0))/(2)` `:. I_(2) = (I_(0))/(2) cos^(2) theta = (I_(0))/(2) cos^(2) 30 = (3I_(0))/(8)` `:. I_(3) = (3I_(0))/(8) cos^(2) theta = (3I_(0))/(8) xx (3)/(4) = (9I_(0))/(32)` `:. I_(4) = (9I_(0))/(32) cos^(2) theta = (9I_(0))/(32) xx (3)/(4)` `(I_(4))/(I_(0)) = (27)/(128)` |
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| 66. |
In geometrical optics, a ray of light is defined asA. path of propagation of lightB. path of propagation of shadowsC. direction of formation of imageD. path of propagation of energy for `lamda to 0` |
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Answer» Correct Answer - D In geometrical optics, a ray is defined as the path of energy propagation in the limit of wavelength tending to zero. The wavelength of visible light was measured and found to be extremely small, e.g. the wavelength of yellow light is about `0.5mum`. Because of the smallness of the wavelength of visible light (in comparison to the dimensions of typical mirrors and lenses), light can be assumed to approximately travel in straight lines. |
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| 67. |
The angle of incidence is equal to angle of reflection is the statement of law ofA. reflectionB. refractionC. gravitationD. length |
| Answer» Correct Answer - A | |
| 68. |
The angle between of the original direction of incident ray and reflected ray isA. angle of deviation due to reflectionB. angle of emergenceC. angle of reflectionD. angle of refraction |
| Answer» Correct Answer - A | |
| 69. |
The angle between reflected ray and normal to the reflecting surface isA. angle of deviationB. angle of incidenceC. angle of refractionD. angle of reflection |
| Answer» Correct Answer - D | |
| 70. |
For a certain light, there are `2 xx 10^(3)` waves in 1.5 mm in air. The wavelength of light isA. 750 nmB. `75 Å`C. `750 Å`D. `75 xx 10^(7) m` |
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Answer» Correct Answer - A Wavelength `= ("Thickness or length of medium")/("Wave no. or of waves")` `= (1.5 xx 10^(-3))/(2 xx 10^(3)) = 750 nm` |
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| 71. |
What will be the colour of sky as seen from the earth, if there were no atmosphereA. BlackB. BlueC. OrganeD. Red |
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Answer» Correct Answer - A The colour of the sky is the colour of light scattered by the particles of the atmosphere. If there were no atmosphere, there will be no particles to scatter light. Hence, the sky will took black. |
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| 72. |
A light wave has a frequency of `4xx10^(14)Hz` and a wavelength of `5xx10^(-7)` meters in a medium. The refractive index of the medium isA. `1.5`B. `1.33`C. `1.0`D. `0.66` |
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Answer» Correct Answer - A `mu_(g) = (v_(a))/(v_(m)) = (v_(a))/(n lambda_(m))` `= (3 xx 10^(8))/(4 xx 10^(14) xx 5 xx 10^(-7)) = 1.5` |
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| 73. |
As polaroid examines two adjacent plane polarised beam A and B whose planes of polarisation are mutually perpendicular. In the first position of the analyser, beam B shows zero intensity. From this position a rotation `30^(@)` shows that thebeams have same intensity. The ratio of intensity of the two beam `I_(Z) & I_(B)`A. `1//2`B. `1//3`C. `3//2`D. `0.83` |
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Answer» Correct Answer - B From Malus law, `I = (I_(0))/(2) cos^(2) theta` In one position the beam B shows zero intensity `:. 90` and for ba, A, `theta = 0` When analyser is rotated through `30^(@)` then `theta = 30^(@)` for beam A and `theta = 60^(@)` for beam B. Now, `I = (I_(A))/(2) cos^(2) 30 = (I_(B))/(2) cos^(2)60` `(I_(A))/(I_(B)) = (cos^(2) 60)/(cos^(2) 30) = (1//4)/(3//4) = (1)/(3)` |
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| 74. |
If the light is polarised by reflection, then the angle between reflected the ray passes from medium to air ?A. `180^(@)`B. `90^(@)`C. `45^(@)`D. `36^(@)` |
| Answer» Correct Answer - B | |
| 75. |
A light ray is travelling from air to medium, c is velocity of light in air and v is velocity of light in medium. The reflected and refracted rays are perpendicular to each other. The angle of polarisation isA. `theta_(P) = tan^(-1)(v//c)`B. `theta_(P) = cos^(-1)(v//c)`C. `theta_(P) = cot^(-1)(v//c)`D. `theta_(P) = sin^(-1)(v//c)` |
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Answer» Correct Answer - C `v_(a) = c, v_(m) = v, theta_(P) = ?` `mu_(m) = (v_(a))/(v_(m)) = tan theta_(P)` `:. theta_(P) = tan^(-1)((v_(a))/(v_(m))) = tan^(-1)((c)/(v))` i.e. `theta_(P) = cot((v)/(c))` |
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| 76. |
Which of the following can not be polarised ?A. Radio wavesB. X-raysC. Ultraviolet raysD. Ultrasonic waves |
| Answer» Correct Answer - D | |
| 77. |
Ordinary light isA. plane polarisedB. partially polarisedC. circularly polarisedD. unpolarised |
| Answer» Correct Answer - D | |
| 78. |
Light waves can be polarised as they areA. have high frequenciesB. have short wavelengthC. are transverseD. can be reflected |
| Answer» Correct Answer - C | |
| 79. |
Which of the following cannot be polarised?A. Ultraviolet raysB. Ultrasonic wavesC. X-raysD. Radio waves |
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Answer» Correct Answer - B Ultrasonic waves cannot be polarised. |
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| 80. |
The first successful astronomical determination of speed of light was made byA. NewtonB. RoemerC. GalieloD. Fizeau |
| Answer» Correct Answer - B | |
| 81. |
Waves that cannot be polarised areA. longitudinal wavesB. transverseC. electromagneticD. can not be predicted |
| Answer» Correct Answer - A | |
| 82. |
The first laboratory determination of the speed of light was made byA. FizeauB. FoucaultC. RoemerD. Michelson |
| Answer» Correct Answer - B | |
| 83. |
The critical angle increases withA. increases in wavelengthB. decreases in refractive indexC. increase in temperatureD. all of these |
| Answer» Correct Answer - D | |
| 84. |
The rays of light which are parallel in nature will formA. spherical wavefrontB. plane wavefrontC. cylindrical wavefrontD. circular wavefront |
| Answer» Correct Answer - B | |
| 85. |
Velocity of electromagnetic waves in a medium depends uponA. thermal properties of mediumB. mechanical and electrical properties of mediumC. electrical and magnetic properties of mediumD. mechanical and magnetic properties of medium |
| Answer» Correct Answer - C | |
| 86. |
A glass slab of thickness `4 cm` contains the same number of waves as `5 cm` of water, when both are traversed by the same monochromatic light. If the refractive index of water is `4//3,` then refractive index of glass isA. 43955B. `1.5`C. 43954D. 16/15 |
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Answer» Correct Answer - C No. of waves `= ("Thickness of medium")/("Wavelength")` Given that same number of waves for glass and water i.e., `(4)/(lambda_(g)) = (5)/(lambda_(w)) :. (lambda_(g))/(lambda_(w)) = (4)/(5)` `mu_(w) = (lambda_(a))/(lambda_(w))` & `mu_(g) = (lambda_(a))/(lambda_(g)) :. (mu_(g))/(mu_(w)) = (lambda_(w))/(lambda_(g))` Thus, `mu_(g) = (lambda_(w))/(lambda_(g)) mu_(w) = (5)/(4) xx (4)/(3) = (5)/(3)` |
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| 87. |
The critical angle depends on theA. refractive indices of the two mediaB. colour of lightC. temperature of lightD. all of these |
| Answer» Correct Answer - D | |
| 88. |
Quantum nature of light is not supported by the phenomenon ofA. compton effectB. photoelectric effectC. emission and absroption of lightD. interference of light |
| Answer» Correct Answer - D | |
| 89. |
The direction of wave normal along which light travels isA. ray of lightB. reflection of lightC. refraction of lightD. interference of light |
| Answer» Correct Answer - A | |
| 90. |
The rays of light corresponding to spherical wavefront areA. converging in natureB. diverging in natureC. parallel in natureD. coaxial |
| Answer» Correct Answer - B | |
| 91. |
In vacuum the speed of light depends uponA. wavelengthsB. frequencyC. amplitudeD. none of these |
| Answer» Correct Answer - D | |
| 92. |
The lateral shift produced due to parallel sided glass slab depends onA. angle of incidenceB. thickness of the glass slabC. the refarctive index of the material of the slabD. all of these |
| Answer» Correct Answer - D | |
| 93. |
Light can not be polarised byA. reflectionB. refractionC. diffractionD. scattering |
| Answer» Correct Answer - C | |
| 94. |
Propagation of light is correctly described in the form ofA. longitudinal wavesB. electromagnetic wavesC. transverse electromagnetic wavesD. stationary waves |
| Answer» Correct Answer - C | |
| 95. |
A perpendicular drawn to the wavefront in the direction of propagation of light isA. wave normalB. ray of lightC. arc of circleD. chord of circle |
| Answer» Correct Answer - A | |
| 96. |
Wave theory of light only can explainA. photoelectric effectB. diffractionC. compton effectD. black body radiation |
| Answer» Correct Answer - B | |
| 97. |
In which of the following phenomena, colours are not produced, if white light is used ?A. DispersionB. PolarisationC. DiffractionD. Interference |
| Answer» Correct Answer - B | |
| 98. |
To explain propagation of light concept of luminiferous ether was introduced byA. NewtonB. HuygenC. MaxwellD. Planck |
| Answer» Correct Answer - B | |
| 99. |
Huygens wave theory is usedA. to determine the velocity of lightB. to find the position of a wavefrontC. to determine the wavelength of lightD. to find the focal length of a lens |
| Answer» Correct Answer - B | |
| 100. |
According to wave theory of light, velocity of light in rarer medium isA. equal to velocity of light in denserB. less than velocity of light in denserC. greater than velocity of light in denserD. cannot predicated |
| Answer» Correct Answer - C | |