Title WAVE OPTICS.pdf ✅

Wave Optics  Digital www.allendigital.in [ 163 ] HUYGEN'S WAVE THEORY OF LIGHT 1. Which of the following phenomenon can not be explained by the Huygen's theory - (1) Refraction (2) Reflection (3) Diffraction (4) Polarization 2. Huygen's principle is applicable to - (1) Only light waves (2) Only sound waves (3) Only mechanical waves (4) For all the above waves 3. According to huygen's theory of secondary wavelets, following can be explained - (1) Propagation of light in medium (2) Reflection of light (3) Refraction of light (4) All of the above 4. Huygen's theory of secondary waves can be used to find- (1) Velocity of light (2) The wavelength of light (3) Wave front geometrically (4) Magnifying power of microscope 5. The main drawback of huygen's theory was- (1) Failure in explanation of rectilinear propagation of lignt (2) Failure of explain the spectrum of white light (3) Failure to explain the formation of newton's rings (4) A failure of experimental verification of ether medium 6. Light has a wave nature, because- (1) The light travel in a straight line (2) Light exhibits phenomenon of reflection and refraction (3) Light exhibits phenomenon of interference (4) Light exhibits phenomenon of photo electric effect 7. Wave nature of light is verified by- (1) Interference (2) Photo electric effect (3) Reflection (4) Refraction INTERFERENCE 8. The energy in the phenomenon of interference: (1) is conserved, gets redistributed (2) is equal at every point (3) is destroyed in regions of dark fringes (4) is created at the place of bright fringes 9. The resultant amplitude in interference with two coherent sources depends upon : (1) only amplitude (2) only phase difference (3) on both the above (4) none of the above 10. Which of following nature of light waves is supported by the phenomenon of interference: (1) longitudinal (2) transverse (3) both transverse and longitudinal (4) None of the above 11. For distinct interference pattern to be observed, necessary condition is that ratio of intensity of light emission by both the sources should be : (1) 2 : 1 (2) 1 : 2 (3) 1 : 1 (4) 1 : 4 12. The phase difference corresponding to path difference of x is : (1) 2 x  (2) 2 x  (3) x  (4) x  13. The coherent source of light produces constructive interference when phase difference between them is : (1)  (2) 1 2  (3) 3 2  (4) 2 14. Phenomenon of interference is not observed by two sodium lamps of same power. It is because both waves have : (1) not constant phase difference (2) zero phase difference (3) different intensity (4) different frequencies 15. Coherent sources can be obtained : (1) only by division of wave front (2) only by division of amplitude (3) both by division of amplitude and wave front (4) none of the above Exercise - I
NEET : Physics [ 164 ] www.allendigital.in  Digital 16. In an interference of light derived from two slit apertures, if at some point on the screen, yellow light has a path difference of 3 2  , then the fringe at that point will be : (1) yellow in colour (2) white in colour (3) dark (4) bright 17. Two beams of light having intensities I and 4I interfer to produce a fringe pattern on a screen. The phase difference between the beam is 2  at point A and 2 at point B. Then find out the difference between the resultant intensities at A and B. (1) 2I (2) 5I (3) I (4) 4I 18. Amplitude of waves observed by two light sources of same wave length are a and 2a and have a phase difference of  between them. Then minimum intensity of light will be proportional to : (1) 0 (2) 5a2 (3) a2 (4) 9a2 19. If the intensity of the waves observed by two coherent sources is I. Then the intensity of resultant wave in constructive interference will be :- (1) 2I (2) 4I (3) I (4)None of the above 20. If intensity of each of the two waves is I and they are having phase difference of 1200, when the waves are superimposed, then the resultant intensity will be : (1) I (2) 2I (3) I/2 (4) 4I 21. Ratio of intensity of two waves is 25 : 1. If interference occurs, then ratio of maximum and minimum intensity should be : (1) 25 : 1 (2) 5 : 1 (3) 9 : 4 (4) 4 : 9 22. The intensity of two waves is 2 and 3 unit, then average intensity of light in the overlapping region will have the value : (1) 2.5 (2) 6 (3) 5 (4) 13 23 The light waves from two independent monochromatic light sources are given by - 1 y 2sin( t kx) =  − and 2 y 3cos( t kx), =  − then the following statement is correct (1) Both the waves are coherent (2) Both the waves are incoherent (3) Both the waves have different time periods (4) None of the above 24. The phenomenon of interference is shown by : (1) Longitudinal mechanical waves only (2) Transverse mechanical waves only (3) Electromagnetic waves only (4) All the above type of waves 25. For the sustained interference of light, the necessary condition is that the two sources should : (1) Have constant phase difference (2) Be narrow (3) Be close to each other (4) Of same amplitude 26. If ratio of amplitude of two interfering source is 3 : 5. Then ratio of intensity of maxima and minima in interference pattern will be : (1) 25 : 16 (2) 5 : 3 (3) 16 : 1 (4) 25 : 9 27. Two coherent light beams of intensity I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are : (1) 5I and 3I (2) 5I and I (3) 9I and 3I (4) 9I and I 28. Two coherent sources of intensities I1 and I2 produce an interference pattern. The maximum intensity in the interference pattern will be : (1) I1 + I2 (2) 2 2 1 2 I I + (3) (I1 + I2) 2 (4) ( ) 2 1 2 I I + 29. Two wave are represented by the equations y1 = a sin t and y2 = a cos t. The first wave : (1) Leads the second by  (2) Lags the second by  (3) Leads the second by 2  (4) Lags the second by 2  30. The resultant amplitude of a vibrating particle by the superposition of the two waves y1 = asin t 3     +     and y2 = a sin t is :- (1) a (2) 2 a (3) 2a (4) 3 a 31. Two coherent sources of different intensities send waves which interfere. If the ratio of maximum and minimum intensity in the interference pattern is 25 then find ratio of intensities of sources : (1) 25 : 1 (2) 5 : 1 (3) 9 : 4 (4) 25 : 16
Wave Optics  Digital www.allendigital.in [ 165 ] 32. What is the path difference of destructive interference : (1) n (2) n( + 1) (3) (n 1) 2 +  (4) (2n 1) 2 +  33. If an interference pattern have maximum and minimum intensities in 36 :1 ratio then what will be the ratio of amplitudes : (1) 5 : 7 (2) 7 : 4 (3) 4 : 7 (4) 7 : 5 34. When a thin transparent plate of thickness t and refractive index  is placed in the path of one of the two interfering waves of light, then the path difference changes by : (1) ( + 1)t (2) ( – 1)t (3) ( 1) t + (4) ( 1) t − 35. Due to effect of interference, floating oil layer in water is visible coloured, due to observation of this event the thickness of oil layer should be : (1) 10 nm (2) 0.1 m (3) 1 mm (4) 10 mm 36. If intensity ratio of two interfering waves is 9 : 1 then ratio of maximum to minimum amplitude of resultant wave is :- (1) 2 : 1 (2) 3 : 2 (3) 1 : 3 (4) 5 : 2 37. For coherent sources which is essential :- (1) colour same (2)  constant (3)  different (4) Amplitude same 38. When exposed to sunlight, thin films of oil on water often exhibit brilliant colors due to the phenomenon of – (1) interference (2) diffraction (3) dispersion (4) polarisation 39. If 1 2 I I = 9 1 then max min I I = ? (1) 100 : 64 (2) 64 : 100 (3) 4 : 1 (4) 1 : 4 40. Soap bubble appears coloured due to the phenomenon of :- (1) Total internal reflection (2) Interference by division of amplitude (3) Interference by division of wavefront (4) Diffraction of light 41. Two coherent light sources emit light of the (1) same intensity (2) different frequency (3) constant phase difference but different wavelengths (4) same frequency having constant phase difference YDSE 42. In Young's experiment, if the amplitude of interferring waves are unequal then the : (1) contrast in the fringes decreases (2) contrast in the fringes increase (3) number of fringes will increase (4) number of fringes will decrease 43. Young's experiment proves that which of the following fact : (1) light is made up of particles (2) light is made up of waves (3) light is made up of neither waves nor particles (4) fringe width doesn't depend upon the spacing between slits. 44. Which of the following statement is true, in Young's experiment, separation between the slits is gradually increased : (1) fringe width increases and fringes disappear (2) fringe width decreases and fringes disappear (3) fringes become blurred (4) fringe width remains constant and fringes are more bright 45. In Young's double slit experiment : (1) only interference occurs (2) only diffraction occurs (3) both interference and diffraction occurs (4) none of the above 46. In Young's double slit experiment, one of the slits is so painted that intensity of light emitted from it is half of that of the light emitted from other slit. Then: (1) fringe system will disappear (2) bright fringes will become brighter and dark fringes will be darker (3) both bright and dark fringes will become darker (4) dark fringes will become less dark and bright fringes will become less bright.
NEET : Physics [ 166 ] www.allendigital.in  Digital 47. In white light interference, nearest to the central (bright) fringe, will have which of the following colour (1) violet (2) yellow (3) red (4) green 48. In Young's double slit experiment, wavelength of light is 6000Å. Then the phase difference between the light waves reaching the third bright fringe from the central fringe will be : (1) zero (2) 2 (3) 4 (4) 6 49. If intensity of each wave in the observed interference pattern in Young's double slit experiment is I0. then for some point P where the phase difference is  , intensity I will be : (1) I = I0 cos (2) I = I0 cos2  (3) I = I0 (1+cos ) (4) I = 2I0(1+cos ) 50. In Young's double slit experiment, bright fringes are of : (1) equal widths and unequal intensities (2) unequal widths and equal intensities (3) equal widths and equal intensities (4) unequal widths and unequal intensities 51. In Young's experiment, monochromatic light through a single slit S is used to illuminate the two slits S1 and S2. Interference fringes are obtained on a screen. The fringe width is found to be w. Now a thin sheet of mica (thickness t and refractive index ) is placed near and in front of one of the two slits. Now the fringe width is found to be w, then : (1) w = w/ (2) w = w (3) w = ( – 1) tw (4) w = w 52. In Young's double slit experiment, the two slits act as coherent sources of equal amplitude A and wavelength  In another experiment with the same set up the two slits are sources of equal amplitude A and wavelength  but are incoherent. The ratio of the intensity of light at the mid-point of the screen in the first case to that in the second case is : (1) 4 : 1 (2) 2 : 1 (3) 1 : 1 (4) None of the above 53. In Young's double slit experiment, if the width of the slits are in the ratio 4 : 9 the ratio of the intensity of maxima to the intensity at minima will be : (1) 169 : 25 (2) 81 : 16 (3) 25 : 1 (4) 9 : 4 54. In an interference experiment, the spacing between successive maxima or minima is : (1) d D  (2) D d  (3) dD  (4) d 4D  55. Young's experiment is performed in air and then performed in water, the fringe width : (1) Will remain same (2) Will decrease (3) Will increase (4) Will be infinite 56. In Young's experiment, one slit is covered with a blue filter and the other with a yellow filter. Then the interference pattern : (1) Will be blue (2) Will be yellow (3) Will be green (4) Will not be formed 57. In Young's double slit experiment, a mica sheet of thickness t and refractive index  is introduced in the path of ray from the first source S1. By how much distance the fringe pattern will be displaced:- (1) ( ) d 1 t D − (2) ( ) D 1 t d − (3) ( ) d −1 D (4) ( ) D 1 d − 58. In Young's experiment, light of wavelength 6000Å is used to produce fringes of width 0.8 mm at a distance of 2.5 m. If the whole experiment is deep in a liquid of refractive index 1.6, then fringe width will be : (1) 0.5 mm (2) 0.6 mm (3) 0.4 mm (4) 0.2 mm 59. If a transparent medium of refractive index  = 1.5 and thickness t = 2.5 × 10–5 m is inserted in front of the slits of Young's Double slit experiment, how much will be the shift in the interference pattern? The distance between the slits is 0.5 mm and that between slits and screen is 100 cm : (1) 5 cm (2) 2.5 cm (3) 0.25 cm (4) 0.1 cm