Tiêu đề 29. Wave optics med.pdf ✅

1. Which the following is correct for light diverging from a point source? (a) The intensity decreases in proportion for the distance squared. (b) The wavefront is parabolic. (c) The intensity at the wavelength does not depend on the distance. (d) None of these 2. Wavefront is the locus of all points, where the particles of the medium vibrate with the same (a) Phase (b) Amplitude (c) Frequency (d) Period 3. A plane wave passes through a convex lens. The geometrical shape of the wavefront that emerges is : (a) Plane (b) Diverging spherical (c) Converging spherical (d) None of these 4. The idea of secondary wavelets for the propagation of a wave was first given by : (a) Newton (b) Huygens (c) Maxwell (d) Fresnel 5. Spherical wavefront, emanating from a point source, strike a plane reflecting surface. What will happen to these wave fronts, immediately after reflection? (a) They will remain spherical with the same curvature, both in magnitude and sign. (b) They will become plane wave fronts. (c) They will remain spherical, with the same curvature, but sign of curvature reversed. (d) They will remain spherical, but with different curvature, both in magnitude and sign. 6. Light propagates rectilinearly , due to: (a) Wave nature (b) Wavelength (c) Velocity (d) Frequency 7. The phenomena which is not explained by huygen’s construction of wave front: (a) Reflection (b) Diffraction (c) Refraction (d) Origin of spectra 8. The wavelength of spectral line coming from a distance star shifts from 600 nm to 600.1nm. The velocity of the star relative to earth is: (a) 1 50kms − (b) 1 100kms − (c) 1 25kms − (d) 1 200kms − 9. The 6563 Å H line emitted by hydrogen in a star found to be red- shifted by 15 Å. The speed with which the star is be receding from the earth is : (a) 5 1 3.2 10 ms−  (b) 5 1 6.87 10 ms−  (c) 5 1 2 10 ms−  (d) 5 1 12.74 10 ms−  10. A galaxy moves with respect to us so that sodium light of 589.0 nm is observed at 589.6 nm. The speed of the galaxy is : (a) 1 206kms − (b) 1 306kms − (c) 1 103kms − (d) 1 51kms − 11. The spectral line for a given element of light received from a distant star is shifted toward longer wavelength side by 0.025%. The velocity of star kin the line of light is: (a) 7.5×104 m s-1 (b) -7.5×104 m s-1 (c) 3.7×104 m s-1 (d) -3.7×104 m s-1 12. The earth is moving towards a fixed star with a velocity of 30 km s-1 . An observer on the earth observes a shift of 0.58 Å in the wavelength of light coming from the star. The actual wavelength of light emitted by the star: (a) 5800 Å (b) 2400 Å (c) 1200 Å (d) 6000 Å 13. The refractive index of glass is 1.5 form light waves of  = 6000Å in vacuum. Its wavelength in galss is : (a) 2000 Å (b) 4000 Å (c) 1000 Å (d) 3000 Å 14. Two light wavesd superimposing at the mid- point of the screen are coming from coherent source of light with phase difference 3 rad. Their amplitudes are 1cm each. The resultant amplitude at the given point will be : (a) 5 cm (b) 3 cm (c) 2 cm (d) Zero 15. Light from two coherent source of the same amplitude A and wavelength  illuminates the screen . The intensity of the central maximum is 0 I if the source were incoherent , the intensity at the same point will be : (a) 10 4/ (b) 2 / 0 (c) I (d) 0 / 2 I 16. An young‘s double slit experiment uses a monochromic source of light. The shape of interference fringes formed ofn the screen is (a) Parabola (b) Straight line (c) Circle (d) Hyperbola 17. Two slits are made one millimeter apart and the screen is placed one metre away. The frings separation when blue green light of wavelength 500 nm is used is: (a) 5 10 m −4  (b) 2.5 10 m −3  (c) 2 10 m −4  (d) 10 10 m −4  18. In a double slit experiment using light of wavelength 600 nm, the angular width of a fringe on a distant screen ;is 0.10 . The spacing between the two slits is : (a) 3.44 10 m −4  (b) 1.54 10 m −4  (c) 1.54 10 m −3  (d) 1.44 10 m −3  19. In Young’s double slit experiment the ratio of intensity of the maxima and minima in the interference experiment is 25:9 The ratio of widths of two slits is: (a) 18:3 (b) 4:1 (c) 8:1 (d) 16:1 20. In the case of light waves from two coherent sources S1 and S2 there will be constructive interference at an arbitrary point P, the path difference S1P − S2P is: (a)       + 2 1 n (b) n (c)       − 2 1 n (d) 2 
21. Intreference fringes were produced in Young’s double slit experiment using light of wavelength 5000Å. When a film of material 2.5×10-3 cm thick was placed over one of the slits, the frings pattern shifted by a distance equal to 20 fringe widths. The refractive index of the material of the film is: (a) 1.25 (b) 1.33 (c) 1.4 (d) 1.5 22. In a double slit experiment the distance between slits is increased ten times whereas their distance from screen is halved then the fringe width is : (a) Becomes 20 1 (b) Becomes 90 1 (c) It remains same (d) Becomes 10 1 23. A laser beam is used for distant objects because: (a) It is monochromatic (b) It is constant (c) It is not observed (d) It has small angular spread 24. The fringes width in a Young’s double slit interference pattern is 2.4×10-4 m, when red light of wavelength 6400 Å is used. How much will it change, if blue light os wavelength 400Å is used? (a) 9×10-4 m (b) 0.9 ×10-4 m (c) 4.5× 10-4 m (d) 0.45 × 10-4 m 25. In Young’s double slit experiment two disturbances arriving at a point P have phase difference of 3  .The intensity of this point expressed as a fraction of maximum intensity 0 I is: (a) 0 I 2 3 (b) 0 I 2 1 (c) 0 I 3 4 (d) 0 I 4 3 26. Two slits in young’s double slit experiment have widths in the ratio 81: 1. The ratio of the amplitudes of light waves is : (a) 3:1 (b) 3:2 (c) 9:1 (d) 6:1 27. When a low flying aircraft passes overhead, we sometimes notice a slight shaking of the picture on our TV screen. This is because of between the direct signal and reflected signal: (a) Interference (b) Diffraction (c) Polaristion of direct singal (d) Both (b) and (c) 28. In a Young’s double slit experiment an electron beam is used to obtain interference patteen. If the speed of electron deceases then: (a) Distance between tow consecutive fringes remains the same (b) Distance between two consecutive fringes decreases (c) Distance between two consecutive fringes increases (d) None of these 29. In a two slit experiment with monochrometic light fringes are obtained on a screen placed a some distance from the plane of slits . If the screen is moves by 53×10-3 m. If the distance between slits is 10-3 m, the wavelength of light will be : (a) 3000Å (b) 4000Å (c) 6000Å (d) 7000Å 30. Two monochromatic light waves of amplitudes 3 A and 2 A interfering at a point have a phase difference of 600 . The intensity at that point will be proportional to : (a) 5A2 (b) 13A2 (c) 7A2 (d) 19A2 31. Consider the following statements in case of Young’s double slite experiment. (1) A site S is necessary if we use an ordinary extended source of light. (2) A slit S is not needed if we use an ordinary but well collimated beam of light. (3) A slit S is not needed if we use a spatially coherent source of light. Which of the above statement are correct? (a) (1), (2) and (3) (b) (1) and (2) only (c) (2) and (3) only (d) (1) and (3) only 32. The colours seen in the reflected white light from a thin oil film are due to: (a) Diffraction (b) Interference (c) Polarisation (d) Dispersion 33. Yellow light of wavelength 6000Å produces fringes of width 0.8 mm in Youngs’s double slit experiment. If the source is replaced by another monochromatic source of wavelength 7500Å and the separation between the slits is doubled then the fringe width beco1mes : (a) 0.1mm (b) 0.8mm (c) 4.3mm (d) 1mm 34. The sources of light of wavelength 2500 Å and 3500Å are used in Young’s double slit experiment simultan -eously. Which orders of frings of two wavelength patterns coincide? (a) 2.4×10-6m (b) 1.2×10-6m (c) 10-6m (d) 0.5×10-6m 35. Two source of light of wavelength 2500Å and 3500Å are used in Young’s double slit experiment simultaneously. Which orders of frings of two wavelength patterns coincide? (a) 3rd order or1st source and 5th of the 2nd (b) 7rd order or1st source and 5th of the 2nd \ (c) 5rd order or1st source and 5th of the 2nd (d) 5rd order or1st source and 5th of the 2nd 36. The two slits are 1mn apart from each of ther and illuminated with a light of wavelength 5 10 m. −7  If the distance of the screen is 1m from the slites, then the distance between third dark frings and fifth bright frings is: (a) 1.2 mm (b) 0.75 mm (c) 1.25 mm (d) 0.625 mm 37. The intensity ratio of the maxima and minima in an interference pattern produced by two coherent source of light is 9:1 The intensities of the used light sources are in ratio: (a) 3:1 (b) 4:1 (c) 9:1 (d) 10:1 38. In a double slit interference pattern, the first maxima for infrared light would be : (a) At the same place as the first maxima for green light (b) Closer to the centre than the first maxima for green light (b) Further from the centre than the first maxima for green light (c) Infrared light does not produce an interference
39. In a double slit experiment, the distance bêtween the slits is d. the screen is at a distance D from the slits. If a bright fringe is formed opposite to one of the slits, is order is: (a)  d (b) dD 2  (c) 2 d D 2  (d) 2D d 2 40. In Young’s double slit experiment, the 10th maximum of wavelength 1 is at a distance y1 from its central maximum and the 5th maximum of wavelength 2 os at a distance y2 from its central maximum. the ratio 2 1 y y will be: (a) 2 1 2   (b) 1 1 2   (c) 2 1 2  (d) 1 1 2  41. What is the minimum thickness of soap film needed for constructive interference in reflected light, if the light incident on the film is 750nm? Assume that the refractive index for the film is  =1.33. : (a) 282 nm (b) 70.5 nm (c) 141 nm (d) 387 nm 42. A narrow slit of width 2 nm is illuminated by monochromatic light of wavelength 500 nm. The distance the first minima on either side on a screen at a distance of 1 m is : (a) 5 nm (b) 0.5 nm (c) 1 nm (d) 10 nm 43. When interference of light takes place: (a) Energy is created in the region of maximum intensity (b) Energy is destroyed in the region of maximum intensity (c) Conservation of energy hold good and energy is redistributed (d) Conservation of energy does not hold good 44. Which of the following is the path difference fro destructive interference? (a) n( +1) (b) ( ) 2 2n 1  + (c) n (d) ( ) 2 n 1  + 45. In Young’s double slit experiment distance between two sources is 0.1mm. The distance of screen from the source is 20cm. Wavelength of light used is 5460Å. Than, angular position of the first dark fringe is: (a) 0.080 (b) 0.160 (c) 0.200 (d) 0.310 46. In a young’s double slit experiment, (slit distance d) monochromatic light of wavelength  is used and the fringe pattern observed at a distance D from the slits. The angular position of the bright fringes are: (a)      −   d N sin i (b)             +  − d ) 2 1 (N sin 1 (c) D N sin−1  (d)             +  − D ) 2 1 (N sin 1 47. The two coherent source with intensity ratio  produced interference. The fringe visiblilty will be: (a) +   1 2 (b) 2 (c) (1+ ) 2 (d) +   1 48. Young’s experiment is performed with light of wavelength 6000Å wherein 16 fringes occupy a certain region on the screen. If 24fringes occupy the same region with another light, of wavelength , then  is: (a) 6000 Å (b) 4500 Å (c) 5000 Å (d) 4000 Å 49. In a Young’s silt experiment, the angular width of a fringe fromed on a distant screen is 10 .The slit separation is 0.01mm. The wavelength of the light is : (a) 0.174 nm (b) 0.174Å (c) 0.174 m (d) 0.174×10-4m 50. In a Young’s double slit experiment let S1 and S2 be the two slits, and C be the center of the screen .If  s1Cs 2 =  and  is the wavelength, the fringe width will be; (a)   (b)  (c)  2 (d)   2 51. In young’s double slit experiment light waves of wavelength 2 5.410 nm and 68.5×101nm are used in turn, keeping the same geometry of the set up. The ratio of the fringe width in two cases is: (a) 1.3 (b) 4.3 (c) 7.9 (d) 9.5 52. A parallel beam of light of wavelength 500nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 1m away. It is observed that the first minima is at a distance of 2.5 mm from the centre of the screen. The width of the slit is : (a) 0.2 nm (b) 1 nm (c) 2 nm (d) 1.5 nm 53. A different pattern is obtained by using beam of red light what will happen, if red light is replaced by the blue light? (a) Bands disapper. (b) Bands become broader and father apart. (c) No change will take place. (d) Diffraction bands become narrow and crowded together. 54. A screen is placed 50 cm from a single slit which is illuminated with light of wavelength 6000Å. If the distance between the first and third minima in the diffraction pattern is 3.0mm. The width of the slit is: (a) 1×10-4 m (b) 2×10-4 m (c) 0.5×10-4 m (d) 4×10-4 m 55. In a single slit different experiment , the width of the slit is made double its original width . Then the central maximum of the diffraction pattern will become : (a) Narrower and fainter (b) Narrower and brighter
(c) Broader and fainter (d) Broader and brighter 56. A parallel beam of light of wavelength 6000Å get diffracted by a single slit of width 0.3 mm. The angular position of the first minima of diffracted light is : (a) 2×10-3 rad (b) 3×10-3 rad (c) 1.8×10-3 rad (d) 6×10-3 rad 57. Consider sunlight incident on a slit of width 104 Å. Get image seen through the slit shall: (a) Be a fine sharp slit white in colour at the centre (b) A bright slit white at the centre diffusing to zero intensities at the edges (c) A bright slit white a the centre diffusing to refions of different colours (d) Only be a diffused slit white in colour 58. Light of wavelength 600nm is incident on an aperture of size 2 nm . The distance upto which light can travel such that its spread is less than the size of the aperture is : (a) 12.13 m (b) 6.67 m (c) 3.33 m (d) 2.19 m 59. A parallel beam of light of wavelength 600nm is incident normally on a of width d. If the distance between the slits and the screen is 0.8m and the distance of 2nd order maximum form the centre of the screen is 15mm. The width of the slit is : (a) 40 m (b) 80 m (c) 160 m (d) 200 m 60. The angular resolution of a 10cm diameter telescope at a wavelength of 5000Å is of the order of : (a) 106 rad (b) 10-2 rad (c) 10-4 rad (d) 10-6 rad 61. In a Frensnel biprism experiment the two positions of lens give separation between the slits as 16cm and 9cm respectively. The actual distance of separation is: (a) 12 cm (b)12.5 cm (c) 13 cm (d) 14 cm 62. For what distance is ray optics a good approximation when the aperture is 4 mm wide and the wavelength is 500 nm? (a) 22 m (b) 32 m (c) 42 m (d) 52 m 63. For the same objective . what is the ratio of the least separation between tow points to be distinguished by a microscope for light of 5000Å and electrons accelerated through 100V used as an illuminating substance? (a) 3075 (b) 3575 (c) 4075 (d) 5075 64. The diatmeter of the pupil of human eye id about 2 mm. Human eyes is most sensitive to the wavelength of 555 nm. the limit of resolution of human eye is : (a) 1.2min (b) 2.4 min (c) 0.6 min (d) 0.3 min 65. If the width of the slit in single slit diffraction experiment is doubled, then the central maximum of diffraction pattern becomes : (a) Broader and brighter (b) Sharper and brighter (c) Sharper and fainter (d) Broader and fainter 66. In young’s double slit expermint, the fringe width of a width light of wavelength 6000Å is 3 mm. the fringe width, when the wavelength of light is changed to 4000Å is : (a) 3 mm (b) 1 mm (c) 2 mm (d) 4 mm 67. A double slit is illuminated by light of wavelength 6000Å. The silt are 0.1 cm apart and the screen is placed 1m away. The angular position of 10th maximum in radian is : (a) 2×10-4 (b) 6×10-4 (c) 3×10-4 (d) 1×10-4 68. A diffraction pattern is obtained using a beam of red light. What happens if the red light is replaced by blue light? (a) No change. (b) Diffraction bands become narrower and crowded together. (c) Band become broader and father apart. (d) Band disappears altogether. 69. Two points separated by distance of 0.1 mm can just be inspected in a microscope when light of wavelength 6000Å is used. If the light of wavelength 4800Å is used then limit of resolution will become : (a) 0.8 mm (b) 0.12 mm (c) 0.1 mm (d) 0.08 mm 70. A slit of width d is illuminated by white light. The first minimum for red light (  = 6500Å )will fall at 0  = 30 when d will be (a) 3200Å (b) 6.5×10-4 (c) 1.3 (d) 2.6×10-4 71. Light is incident on a glass surface at polarizing angle of 57.50 .Then the angle between the incident ray and the refracted ray is : (a) 57.50 (b) 1150 (c) 2050 (d) 1450 72. A transparent thin plate of Polaroid is placed on another similar plate such that the angle between their axes is 300 . The intensities of the emergent and the unpolarized incident light will be in the ratio of : (a) 1:4 (b) 1:3 (c) 3:4 (d) 3:8 73. The critical angle of a certain medium is sin-1       5 3 the polarizing angle of the medium is: (a) sin-1       5 4 (b) tan-1       3 5 (c) tan-1       4 3 (d) tan-1       3 4 74. In the case of linearly polarized light, the magnitude of the electric field vector: (a) Is parallel to the direction of propagation (b) Does not change with time (c) Increases linearly with time (d) Varies periodically with time 75. When angle of incidence is 600 on the surface of a glass slab, it is found that the reflected ray is completely polarized . The velocity of light in glass is : (a) 8 1 2 10 ms−  (b) 8 1 3 10 ms−  (c) 8 1 2 10 ms−  (d) 8 1 3 10 ms−  76. The velocity of light in air is 3×108 m s-1 and that in water is 2.2×108 m s-1 . The polarizing agnle of incidence is: (a) 450 (b) 500 (c) 53.740 (d) 630