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Physics by Shivendra Singh, , Interference, Q.1, , (C), , 7.692, , , (D), , (B) The frequency and amplitude of both the, waves should be same, (C) The propagation of waves should be, simultaneously and in same direction, , 7.692, 3, , (D) All of the above, , The similarity between the sound waves and, light waves is –, , Q.11, , (A) Both are electromagnetic waves, (B) Both are longitudinal waves, , (B) Of same amplitude, frequency but with, varying phase difference and of same, state of polarisation, , Monochromatic light is that light in which, (A) Single wavelength is present, (B) Various wavelengths are present, , (C) Of same frequency constant phase, difference and of different sate of, polarisation, , (C) Red and violet light is present, (D) Yellow and red light is present, Q.4, , The colours are ascertained by –, (A) Wavelength, (C) Speed, , Q.5, , Q.6, , Intensity of light depends on –, , (B), , 2, , , (C), , , 2, , (D), , T, , 2, , (C)  = 2, , 2, , T, , (D)  =, 2, , (B) Depend upon time, (C) Change at constant rate, (D) Not depend upon time, Q.13, , Interference event is observed in, (A) Only transverse waves, (B) Only longitudinal waves, , (B)   =, , (C) Both types of waves, (D) Not observed in both type of waves, Q.14, , In the phenomenon of interference, energy is, (A) Destroyed at bright frings, (B) Created at dark fringes, (C) Conserved, but it is redistributed, (D) Same at all points, , Q.15, , (B) Only phase difference, , The nature of light which is verified by the, interference event is –, (A) Particle nature, (B) Wave nature, (C) Dual nature, , (C) On both the above, , (D) Quantum nature, , The path difference between two waves, y1= A1 sin t and y2= A2 cos (t + ) will, be, (A) (/2) (B) (/2) (+/2), (C) (2/) (–2), , Q.9, , For a persistent interference to occur, it is, necessary that phase difference of waves, should –, (A) be zero, , , , , The correct relation between time interval , and phase difference  is –, (A)  =, , Q.8, , Q.12, , (B) Frequency, (D) Velocity, , The ratio of phase difference and path, difference is –, (A) 2, , Q.7, , (D) Of same amplitude, different frequency,, constant phase difference and of same, state of polarisation, , (B) Amplitude, (D) Intensity, , (A) Amplitudes, (C) Wavelength, , The necessary condition for interference, pattern of light is that light sources should, be –, (A) Of same amplitude, frequency, constant, phase difference and of same state of, polarisation, , (C) Both have the same speed in a medium, (D) They can produce interference, Q.3, , The necessary condition for phenomenon of, interference to occur is, (A) There should be two coherent sources., , (B) 7.692 , , (A) 7.692, , Q.2, , Q.10, , The path difference between two wavefronts, emitted by coherent sources of wavelength, 5460 Å is 2.1 micron . The phase difference, between the wavefronts at that point is –, , (D) (2/) , , The resultant amplitude in interference with, two coherent source depends upon –, (A) Intensity, , (D) None of the above, Method Guru -Shastri Nagar, Sultanpur, 7014344748

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Physics by Shivendra Singh, Q.16, , (A) Two different lamps, (B) Two different lamps but of the same power, (C) Two different lamps of same power and, having the same colour, (D) None of these, , The phenomenon of interference is based, on the principle of –, (A) Diffraction, (C) Refraction, , (B) Superposition, (D) Polarisation, , Q.17, , For constructive interference the path, difference should be ( = wavelength of light), (A) Even multiple of /2, (B) Odd multiple of /2, (C) Even or odd multiple of /2, (C) None of the above, , Q.18, , The equation for two waves obtained by two, light sources are as given below :, , Q.25, , Coherence is measure of –, (A) Capability of producing interference by, waves, (B) Waves being diffracted, (C) Waves being reflected, (D) Waves being refracted, , Q.26, , In coherent sources it is necessary that their, (A) Amplitudes are same, (B) Wavelengths are same, (C) Frequencies are same, (D) Initial phase remains constant, , Q.27, , Two coherent sources can be obtained by –, (A) Division of wavefront only, (B) Division of amplitude only, (C) both by division of wavefront and amplitude, (D) None of the above, , Q.28, , Two independent monochromatic sodium, lamps can not produce interference because, (A) The frequencies of two sources are, different, (B) The phase difference between two sources, changes with respect to time, (C) The two sources become coherent, (D) The amplitudes of two sources are, different, , Q.29, , In Young's double slit experiment the ratio of, , y1= A1 sin 3t, y2 = A2 cos (3t + /6)., What will be the value of phase difference, at the time t –, (A) 3/2, Q.19, , (C) , , (B) 2/3, , (D) /2, , The maximum intensity produced of two, coherent waves of intensity I1 and I2 will be, (A) I1 + I2, (B) I12 + I22, (C) I1 + I2 + 2 I1 I 2, (D) zero, , Q.20, , Two coherent waves are represented by, y1= a1 cost and y2 = a2 sin  t. The, resultant intensity due to interference will, be –, (A) (a1 + a2), (C) (a12 + a22), , Q.21, , Q.22, , Q.23, , Q.24, , (B) (a1 – a2), (D) (a12 – a22), , Two coherent sources have intensity ratio of, 100 : 1, and are used for obtaining the, phenomenon of interference. Then the ratio, of maximum and minimum intensity will be, –, (A) 100 : 1, (B) 121 : 81, (C) 1 : 1, (D) 5 : 1, Two phase coherent sources of intensity, ratio 4 coincides. Visibility in the interference, pattern will be –, (A) 1/4, (B) 1/5 (C) 3/4, (D) 4/5, Two independent mono-chromatic sources, of light are, (A) Coherent, (B) Incoherent, (C) Coherent or incoherent depending upon, the nature of source, (D) None of the above, Two coherent sources of light can be, obtained by, , the slit widths is 1 :4. The ratio of maximum, and minimum intensities in the interference, pattern will be –, , Q.30, , (A) 4 : 9, , (B) 9 : 4, , (C) 9 : 1, , (D) 1 : 9, , The Young's double slit experiment is, performed in succession using blue light of, wavelength 4360Å and green light of, wavelength 5460Å. If the distance of fourth, maximum from central maximum is x, then –, (A) xblue > xgreen, (B) xblue < xgreen, (C) xblue = xgreen, (D), , x blue, 5460, =, x green, 4360, , Method Guru -Shastri Nagar, Sultanpur, 7014344748

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Physics by Shivendra Singh, Q.38, Q.31, , In Young's double slit experiment 62 fringes, are visible in the field of view with sodium, light ( = 5893Å). If green light ( = 5461Å), is used then the number of visible fringes will, Q.39, , be –, (A) 62, Q.32, , (B) 67, , (C) 85, , (D) 58, , In Young's experiment coherent sources are, (A) Division of wave front, , Mark the correct statement while performing, Young's experiment the width of the slits is, gradually increased, then, , (C) Fringes get blurred, , (D) None of the above, , (D) Fringe width remains constant and they, appear brighter, , In Young's double slit experiment, the, Q.40, ,  2d , , (B) n , D , , D, 4d, (D) (2n-1), 2d, D, The coherent source of light produces, constructive interference when phase, difference between them is, 3, 1, (A) , (B)  (C)  (D) 2, 2, 2, The interference fringes produced by, mono-chromatic light here –, (A) Equal intensity, , (C) Wavelength of the light used, (D) Distance between slits and screen, Q.41, , Q.42, , (B) Equal width, (C) All the bright fringes and all the dark, fringes have uniform brightness and, darkness and the width of fringes is also, equal, (D) The intensity all bright is same the, darkness of all dark fringes is also same, but have different widths, If the yellow light is replaced by the violet, light then the interference fringes(A) Will become fainter, (B) Will become brighter, (C) The fringe width will increase, (D) The fringe width will decrease, In Young's double slit experiment with, monochromatic light the central fringe will be, , The fringe width in a Young's double slit, experiment can be increased. If we decrease, (A) Width of the slits, (B) Separation of the slits, , (C) 2n  1, , Q.37, , (D) White, , (C) Division of wave front and amplitude, ,  D , , (A) n , 2d , , Q.36, , (C) coloured, , (B) Fringe width decreases and finally the, fringes disappear, , centre is –, , Q.35, , (B) Bright, , (B) Division of amplitude, , distance of the n-th dark fringe from the, , Q.34, , (A) Dark, , (A) Fringe width increase and finally the, fringes disappear, , produced by, , Q.33, , If the path difference between the interfering, waves is n, then the fringes obtained on the, screen will be, , If in Young's double slit experiment, the, distance between the slits is halved and the, distance between slit and screen is doubled,, then the fringe width will become –, (A) half, , (B) double, , (C) four times, , (D) unchanged, , What happens when the width of slit aperture, is increased by keeping 'd' as constant in, Young's experiment (A) Fringe width will increase, (B) Fringe width will decrease, (C) Fringe width will remain unchanged, (D) Gradually the fringes will be disappear, , Q.43, , In Young's double slit experiment, the value, of intensity at the site of constructive, interference, should be equivalent to which of, the following –, (A) Sum of intensities of both sources, (B) Twice the sum of intensities of both, sources, (C) Difference of intensities of both sources, (D) Four times the sum of intensities of both, sources, , (A) Coloured, , (B) White, , (C) Bright, , (D) Black, Method Guru -Shastri Nagar, Sultanpur, 7014344748

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Physics by Shivendra Singh, Q.44, , Q.45, , Q.46, , In young's double slit experiment, interference, pattern is observed on the screen L distance, apart from slits, average distance between, adjacent fringes is x and slits separation is, d, then the wavelength of light will be –, (A) xd/ L, , (B) xL/d, , (C) Ld/x, , (D) Ldx, , (D) Prism angle, the prism material and the, distance between the screen and the, prism., Q.51, , (A) increases, , In biprism experiment the light source is –, (A) extended, , (B) narrow, , (C) multichromatic, , (D) all of above, , In Fresnel's biprism experiment the coherent, sources are obtained by –, (A) interference, , (B) Decreases, (C) Remains unchanged, (D) Increases in the beginning but decreases, when lt reaches maximum, , Diffraction and Polarisation, Q.1, , (B) reflection, (C) refraction, , Q.48, , In Fresnel biprism experiment the distance, between the source and the screen is 1 m, and that between the source and biprism is, 10 cm. The wavelength of light used is 6000, Å. The fringe width obtained is 0.03 cm and, the refracting angle of biprism is 1º. The, refractive index of the material of biprism is(A) 1.531, , (B) 1.573, , (C) 1.621, , (D) 1.732, , Q.2, , (C) Of the same order as the wavelength of, light used, (D) Bears no relation with the wavelength of, light used, Q.3, , (C) Hyperbolic, , Q.50, , Who first discovered the phenomenon of, diffraction, (A) Fresnel, (C) Arago, , (D) Straight line, If Fresnel's biprism experiment, resultant, amplitude depends upon-, , The phenomenon of diffraction can be, observed, when the obstacle is -, , (B) Quite small as compared to the, wavelength of light used, , (A) Cylindrical, , Q.49, , (B) Reflection, (D) Interference, , (A) Quite large as compared to the, wavelength of light used, , In Fresnel's biprism, the form of the fringes is, (B) Elliptical, , The bending of a beam of light around, comers of an obstacle is called (A) Refraction, (C) Diffraction, , (D) total internal reflection, Q.47, , In fresnel's biprism experiment, when the, distance between the slit aperture and eye, is increased, then distance between the, fringes-, , (A) Only amplitude, , The occurrence of diffraction pattern depends, on, , (B) Only intensity, , (A) The width of slit, , (C) Only phase difference, , (B) Wavelength of light, , (D) Both the phase difference and the, amplitude, , (C) Relative sizes of width of slit and, wavelength, , In Fresnel's experiment, the distance between, imaginary sources formed, depends upon, the, , (D) Neither the width of slit nor wavelength, , (A) Material of the prism and the distance, between prism and the slit, (B) Prism angle and the distance between, prism and the slit, (C) Prism angle and the distance between, prism and the slit and the prism material, , Q.4, , (B) Fraunhofer, (D) Grimaldi, , Q.5, , Light after being a wave motion, appears to, travel in straight line because (A) Velocity of light more, (B) Frequency of light is less, (C) Wave length of light is less, (D) None of thes, , Method Guru -Shastri Nagar, Sultanpur, 7014344748

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Physics by Shivendra Singh, Q.6, , Phenomenon of diffraction occurs -, , Q.11, , What is necessary for easy occurrence of, Fresnel’s diffraction (A) Obstacle should be of the order of wave, length, (B) Narrow opening should be of the order of, wave length, (C) Source and screen should be at finite, distance from the obstacle, (D) All of the above, , Q.12, , The correct relation between the size of the, obstacle and the wavelength of light in order, to observe the diffraction event is -, , (A) Only in case of light and sound waves, (B) For all kinds of waves, (C) For electromagnetic waves and not for, matter waves, (D) For-light waves but not is case of X-rays, Q.7, , Diffraction of light is observed only, when the, obstacle size is (A) Very large, (B) Very small, , a, > 1, , a, (C), = , , , (C) Of the same order that of wavelength of, , (A), , light, (D) Any size, Q.8, , Diffraction of sound is more evident in daily, lifte than light waves, because the than, , Q.13, , In young’s double slit experiment, the, diffraction is of the type, (A) Fresnel, (B) Fraunhoffer, (C) Both Fresnel and Fraunhoffer, (D) Neither Fresnel nor Fraunboffer, , Q.14, , The diffraction effect of light expresses that, (A) Light is transverse wave motion, (B) Light is wave motion, (C) Light is longitudinal wave motion, (D) Light has quantum nature, Which colour should be used to increase, the resolving power of a microscope (A) Violet, (B) Red, (C) Yellow, (D) Green, Central fringe obtained in diffraction pattern, due to a single slit (A) is of minimum intensity, (B) is of maximum intensity, (C) intensity depends upon slit width, (D) None of the above, , diffraction of light. Because the, (A) Wave length of sound waves is greater, than that of light, (B) Sound waves are longitudinal, while light, waves are transverse, (C) Velocity of sound waves is less than that, of light, (D) None of the above, Q.9, , If the wave length of a wave is large the, , Q.15, , degree of diffraction observed is, (A) Less (B) More, (C) Zero, Q.10, , (D) Insufficient information, , Q.16, , The main difference between the phenomena, of interference and diffraction is that (A) Diffraction is due to interaction of light, from the same wave front, whereas, interference is the interaction of waves, , a, = 0, , a, (D), = 150, , , (B), , Q.17, , In the diffraction pattern of a single slit, aperture, the width of the central fringe, compared to widths of the other fringes, is, (A) Equal, (B) Less, (C) Little more, (D) Double, , Q.18, , from the same source, while interference, , What happens, when the width of the slit, aperture, is increased in an experiment of, single slit diffraction, , is superposition of light from wavefront., , (A) Spread of diffraction region is increased, , (D) In both diffraction and interference,, , (B) Spread of diffraction region is decreased, , number of coherent the same sources is, , (C) Spread of diffraction region will be, decreased but mid-band becomes narrow, , from two separate sources., (B) Diffraction is due to superposition of light, from the same wavefront, whereas, interference is due to two waves derived, from the same source., (C) Diffraction is due to two waves derived, , two, , (D) None of above, Method Guru -Shastri Nagar, Sultanpur, 7014344748

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Physics by Shivendra Singh, Q.19, , In a single slit diffraction pattern, if the light, source is used of less wave length then, previous one. Then width of the central fringe, will be (A) Less, (C) Unchanged, , Q.20, , (B) Increase, (D) None of these, , For fraunhoffer single slit diffraction, , Q.26, , (A) corpuscular nature of light, (B) quantum nature of light, (C) transverse wave nature of light, (D) longitudinal wave nature of light, Q.27, , (A) light waves, (B) electromagnetic waves, , (B) On increasing the slit width, the width of, central maxima decreases., , (D) longitudinal waves, , (C) transverse waves (D), Q.28, , (D) All of the above are correct, The positions of minima in the diffraction, pattern due to a single slit are expressed by, the formula(A) a sin  = n, , (D) a sin = (2n – 1) ×, , (A) sin–1 (n), , (B) sin–1 (1/n), , (C) tan–1 (1/n), , (D) tan–1 (n), , The polaroid glass is used in sunglasses, as (B) this reduce glare, (C) this is cheaper than other types, (D) this looks more beautiful, , , 2, , The fringe width in single slit diffraction, pattern is proportional to, (A) a/, , Q.23, , Q.29, , The angle of incidence at which reflected light, is totally polarised for reflection from air to, glass (refractive index n) is -, , (A) it is a fashion, , , (B) a sin  =(2n + 1), 2, n, (C) a sin  =, 2, , Q.22, , Waves that cannot be polarised are -, , (A) Width of central maxima is proportional, to, , (C) On making the slit width a = , central, spreads in the range ± 90º, , Q.21, , Polarisation of light proves the -, , (B) /a, , (C) a, , (D) , , The condition for obtaining maxima in the, diffraction pattern due to a single slit is (A) a sin  = (2n – 1), , , 2, , (B) a sin = n, , n, 2, (D) a sin = (2n + 1), (C) a sin =, , Q.24, , For n th order maxima in Fraunhoffer, diffraction by a single slit aperture, the value, of path difference should be, (A) n, (C) /2 (2n + 1), , Q.25, , (B) 2n, (D) (2n + 1), , A slit of width 12 × 10–7 m is illuminated by, light of wavelength 6000Aº. The angular width, of the central maximum is approximately (A) 30º, , (B) 60º, , (C) 90º, , (D) 0º, , Method Guru -Shastri Nagar, Sultanpur, 7014344748

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Physics by Shivendra Singh, , Answer Key, Interference, Q.No., Ans., Q.No., Ans., Q.No., Ans., , 1, B, 21, B, 41, C, , 2, D, 22, D, 42, D, , 3, A, 23, B, 43, B, , 4, A, 24, D, 44, A, , 5, A, 25, A, 45, B, , 6, B, 26, D, 46, C, , 7, A, 27, C, 47, B, , 8, B, 28, B, 48, C, , 9, C, 29, C, 49, D, , 10, D, 30, B, 50, C, , 11, A, 31, B, 51, A, , 12, D, 32, A, , 13, C, 33, C, , 14, C, 34, D, , 15, B, 35, C, , 16, B, 36, C, , 17, A, 37, C, , 18, B, 38, B, , 19, C, 39, C, , 20, C, 40, B, , Diffraction and Polarisation, Q.No., Ans., Q.No., Ans., , 1, C, 21, A, , 2, C, 22, B, , 3, D, 23, A, , 4, C, 24, C, , 5, C, 25, B, , 6, B, 26, C, , 7, C, 27, D, , 8, A, 28, D, , 9, B, 29, B, , 10, B, , 11, D, , 12, A, , 13, B, , 14, B, , 15, A, , Method Guru -Shastri Nagar, Sultanpur, 7014344748, , 16, B, , 17, D, , 18, C, , 19, A, , 20, D