This quiz works best with JavaScript enabled. Home > Cbse > Class 12 > Science > Physics Part Ii > Class 12 Physics (Part Ii) Chapter 10 Wave Optics – Quiz 1 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part Ii) Chapter 10 Wave Optics Quiz 1 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. When compact disk is illuminated by a source of white light, coloured lines are observed. This is due to A) Diffraction. B) Dispersion. C) Interference. D) Refraction. Show Answer Correct Answer: A) Diffraction. 2. An object is placed at a distance of 0.5 m in front of a plane mirror. The distance between object and image will be: A) 2.0 m. B) 1.0 m. C) 0.5 m. D) 0.25 m. Show Answer Correct Answer: B) 1.0 m. 3. Two beams of coherent light are shining on the same piece of white paper. With respect to the crests and troughs of such waves, darkness will occur on the paper where: A) The crests from both waves overlap. B) The crest from one wave overlaps with the trough from the other. C) The troughs from both waves overlap. D) Darkness cannot occur as the two waves are coherent. Show Answer Correct Answer: B) The crest from one wave overlaps with the trough from the other. 4. The fringe width in interference is: A) Directly proportional to slit separation. B) Inversely proportional to wavelength. C) Directly proportional to wavelength. D) Inversely proportional to slit width. Show Answer Correct Answer: C) Directly proportional to wavelength. 5. What is common with all electromagnetic and mechanical waves? A) They travel at the same speed. B) They transfer energy. C) They are all longitudinal waves. D) They are all transverse waves. Show Answer Correct Answer: B) They transfer energy. 6. How does the diffraction band of blue light look in comparison with the red light? A) No changes. B) Diffraction pattern becomes broader. C) Diffraction pattern becomes narrower. D) Diffraction pattern disappears. Show Answer Correct Answer: C) Diffraction pattern becomes narrower. 7. Two coherent sources of light can be obtained by ..... 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 the above. Show Answer Correct Answer: D) None of the above. 8. Young's double slit experiment has two slits. A) True. B) False. C) Both a and b. D) None of the above. Show Answer Correct Answer: A) True. 9. For a total internal reflection, which of the following is correct? A) Light travels from denser to rarer medium. B) Light travels in air only. C) Light travels from rarer to denser medium. D) Light travels in water only. Show Answer Correct Answer: A) Light travels from denser to rarer medium. 10. Light is considered to be A) Electromagnetic waves. B) Particles. C) Transverse waves. D) All of the above. Show Answer Correct Answer: D) All of the above. 11. Bending of light at sharp edges of obstacles is due to A) Polarization. B) Interference. C) Refraction. D) Diffraction. Show Answer Correct Answer: D) Diffraction. 12. Approximately how much light is blocked by a single polarizing filter? A) 75%. B) 100%. C) 0%. D) 50%. Show Answer Correct Answer: D) 50%. 13. Which would have the widest-spaced fringe pattern for light traveling through a diffraction grating? A) Large wavelength and a small slit spacing. B) Small wavelength and small slit spacing. C) Large wavelength and a large slit spacing. D) Small wavelength and a large slit spacing. Show Answer Correct Answer: A) Large wavelength and a small slit spacing. 14. The refractive index of glass is 1.5 for light waves of X = 6000 A in vacuum. Its wavelength in glass is A) 2000. B) 1000. C) 3000. D) 4000. Show Answer Correct Answer: D) 4000. 15. In Fraunhofer class of diffraction A) The source and screen are at infinite distance. B) The source is at finite distance and screen is at infinite distance. C) The source and screen are at a finite distance. D) The source is at infinite distance and screen is at a finite distance. Show Answer Correct Answer: A) The source and screen are at infinite distance. 16. What is path difference for destructive interference? A) (2n + 1)$\lambda$/2. B) N($\lambda$ +1). C) (n +1)$\lambda$/2. D) N$\lambda$. Show Answer Correct Answer: A) (2n + 1)$\lambda$/2. 17. Bending of light from sharp edges is called A) Reflection. B) Refraction. C) Dispersion. D) Polarisation. Show Answer Correct Answer: C) Dispersion. 18. If the velocity of light in a medium depends on its frequency, the medium is said to be A) Resonant. B) Refractive. C) Diffractive. D) Dispersive. Show Answer Correct Answer: D) Dispersive. 19. The wavefront due to a source situated at infinity is A) Cylindrical. B) Circular. C) Planar. D) Spherical. Show Answer Correct Answer: C) Planar. 20. For Young's double slit interference the fringe width $\beta$ A) $\frac{D}{\lambda d}$. B) $\frac{d}{\lambda D}$. C) $\frac{\lambda d}{D}$. D) $\frac{\lambda D}{d}$. Show Answer Correct Answer: D) $\frac{\lambda D}{d}$. 21. The idea of secondary wavelets for the. propagation of a wave was first given by A) Huygens. B) Maxwell. C) Newton. D) Fresnel. Show Answer Correct Answer: A) Huygens. 22. What is the minimum distancebetween two objects which can be resolvedby a microscope having the visual angle of300 when light of wavelength 500 nm is used? A) 4.1 x 10$^{7}$m. B) 3.1 x10$^{-8 }$m. C) 6.1 x 10-7 m. D) 7.1x 10$^{-7}$m. Show Answer Correct Answer: C) 6.1 x 10-7 m. 23. The centre of interference pattern is A) Always bright. B) Always dark. C) May be bright or dark. D) Brightness changes continuously. Show Answer Correct Answer: A) Always bright. 24. The bending of a wave caused by a change in its speed as it moves from one medium to another. A) Reflection. B) Rarefaction. C) Refraction. D) None of the above. Show Answer Correct Answer: C) Refraction. 25. Which of the following phenomena can explain quantum nature of light ..... A) Interference. B) Polarisation. C) Diffraction. D) Photoelectric effect. Show Answer Correct Answer: D) Photoelectric effect. 26. In the context of wave optics, what does 'path difference' refer to? A) The difference in frequency of two waves. B) The difference in amplitude of two waves. C) The difference in phase of two waves. D) The difference in distance traveled by two waves. Show Answer Correct Answer: D) The difference in distance traveled by two waves. 27. In Fresnel diffraction, the observed pattern changes if: A) The wavelength remains the same. B) The speed of light changes. C) The slit width remains the same. D) The screen distance changes. Show Answer Correct Answer: D) The screen distance changes. 28. Light in a vacuum has wavelength, $\lambda$. What is the wavelength of light upon entering a material with an index of refraction, n? A) $n\lambda$. B) $\frac{n}{c\lambda}$. C) $\frac{n}{\lambda}$. D) $\frac{\lambda}{n}$. Show Answer Correct Answer: D) $\frac{\lambda}{n}$. 29. The ..... is equal to the ratio of the speed of light in vacuum (c) to the speed of light in the medium (v). A) Wavefront. B) Permittivity. C) Refractive index. D) Permeability. Show Answer Correct Answer: C) Refractive index. 30. The maximum number of possible interference maxima for the slit separation equal to twice the wavelength is in YDSE A) Infinity. B) Zero. C) Five. D) Three. Show Answer Correct Answer: C) Five. 31. A diffraction grating with 10, 000 lines per centimeter will exhibit the first-order maximum for light of wavelength 510 nm at what angle? A) 15.3$^{o}$. B) 31$^{o}$. C) 0.62$^{o}$. D) 0.51$^{o}$. Show Answer Correct Answer: B) 31$^{o}$. 32. The shape of waverfront for a light emerging out of a convex lens when a point source is placed at its focus A) Plane wavefront. B) Soherical wavefront. C) All the above. D) None of the above. Show Answer Correct Answer: A) Plane wavefront. 33. The points of the wave front of light are the sources of smaller waves called wavelets. A) Hubble. B) Huygen. C) Mahathir. D) Grimaldi. Show Answer Correct Answer: B) Huygen. 34. As per Huygens principle, wavelets originating on a wavefront grow with A) Slow speed. B) Same speed. C) More speed. D) None of these. Show Answer Correct Answer: B) Same speed. 35. Diffraction is waves bending because of A) Gravity. B) Dark matter. C) Edges of a slit or thin object. D) Speed of wave changes. Show Answer Correct Answer: C) Edges of a slit or thin object. 36. The frequency of a light wave in a material is 2 x 10$^{14}$ Hz and wavelengthis 5000A$^{o}$. The refractive index of material is A) 1.33. B) 1.40. C) 1.50. D) 3.00. Show Answer Correct Answer: D) 3.00. 37. According to Huygens' principle, light is a form of A) Particle. B) Rays. C) Wave. D) Radiation. Show Answer Correct Answer: C) Wave. 38. . In a Young's double slit experiment, two slits of equal width are arranged symmetrically w.r.to the sources. The intensity of the central bright fringe is I. If one of the slits is closed, the intensity at the Centre of the screen will be A) I/2. B) I. C) I/4. D) 2I. Show Answer Correct Answer: C) I/4. 39. A plane wavefront passes through a small circular aperture. What will be the shape of the wavefront emerging on the other side? A) Plane. B) Elliptical. C) Spherical. D) Cylindrical. Show Answer Correct Answer: C) Spherical. 40. What do you mean by the Rayleigh criterion? A) When the central maximum of one source coincides with the first minimum of the other. B) When the central maximum of one source overlap with the central maximum of the other. C) When the central maximum of one source overlap with the first minimum of the other. D) None of the above. Show Answer Correct Answer: A) When the central maximum of one source coincides with the first minimum of the other. 41. Which phenomenon is observed when light passes through a narrow slit and spreads out? A) Diffraction. B) Interference. C) Refraction. D) Reflection. Show Answer Correct Answer: A) Diffraction. 42. According to Huygens' principle: A) The new wavefront can be taken in forward as well as in backward direction. B) Each wavelet is a source of new wavefront. C) The speed of secondary wavelets is lesser than the speed of primary wavelets. D) Each point on wavefront is a source of secondary wavelet. Show Answer Correct Answer: D) Each point on wavefront is a source of secondary wavelet. 43. According to Huygens principle of secondary wavelets, each particle at a wave front A) Behaves as a new light source. B) Behaves as a photon. C) Is an electron. D) Represents the direction of the motion of wave front. Show Answer Correct Answer: A) Behaves as a new light source. 44. A wave front is an imaginary surface where A) All particles lying on this vibrate in opposite phase. B) Some particles in same phase and some in opposite phase. C) All particles lying on this vibrate in same phase. D) None of these. Show Answer Correct Answer: C) All particles lying on this vibrate in same phase. 45. In YDSE the ratio of maximum to minimum intensities of the fringe system is 4:1. The amplitudes of the coherent sources are in the ratio A) 1:1. B) 4:1. C) 2:1. D) 3:1. Show Answer Correct Answer: D) 3:1. 46. Reciprocal of the limit ofresolution is called ..... A) Angle of resolution. B) Resolving power. C) Dispersive power. D) Polarization. Show Answer Correct Answer: B) Resolving power. 47. Which of the following real-world phenomena demonstrates the superposition of sound waves? A) Laser beam coherence. B) Beats heard when two tuning forks are struck. C) Bending of light in water. D) A rainbow forming after rain. Show Answer Correct Answer: B) Beats heard when two tuning forks are struck. 48. Which of the following phenomenon is not explained by Huygen's wave theory? A) Diffraction. B) Interference. C) Photoelectric effect. D) None of these. Show Answer Correct Answer: C) Photoelectric effect. 49. Consider sunlight incident on a slit of width 104 A. The image seen through the slit shall A) Be a fine sharp slit white in colour at the center. B) A bright slit white at the center diffusing to regions of differentcolours. C) Only be a diffused slit white in colour. D) A bright slit white at the center diffusing to zero intensities atthe edges. Show Answer Correct Answer: A) Be a fine sharp slit white in colour at the center. 50. What is the effect of increasing the wavelength of light in a Michelson interferometer? A) Decreases the fringe spacing. B) Causes the fringes to disappear. C) Increases the fringe spacing. D) No effect on fringe spacing. Show Answer Correct Answer: C) Increases the fringe spacing. 51. What is the function of the beam splitter in a Michelson interferometer? A) To absorb unwanted light. B) To polarize the beam. C) To rotate the beam direction. D) To divide the incoming beam into two perpendicular paths. Show Answer Correct Answer: D) To divide the incoming beam into two perpendicular paths. 52. In Newton's ring experiments, the diameter of dark rings is proportional to A) Square roots of odd natural numbers. B) Even natural number. C) Odd natural number. D) Square root of natural number. Show Answer Correct Answer: D) Square root of natural number. 53. The distance between 2 corresponding parts of a wave (example-crest to crest) is its ..... A) Amplitude. B) Trough. C) Wavelength. D) Frequency. Show Answer Correct Answer: C) Wavelength. 54. Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are: A) 5I and I. B) 5I and 3I. C) 9I and I. D) 9I and 3I. Show Answer Correct Answer: C) 9I and I. 55. Mirage is a phenomenon due to: A) Diffraction of light. B) Total internal reflection of light. C) Refraction of light. D) Reflection of light. Show Answer Correct Answer: B) Total internal reflection of light. 56. When we look through rainbow glasses ..... (diffraction-slits) ..... which color is bent the least (shows up closest to the object) A) Violet. B) Red. C) Green. D) Yellow. Show Answer Correct Answer: A) Violet. 57. In Young's double slit experiment, if the monochromatic source of yellow light is replaced by red light, the fringe width A) Remains unchanged. B) Decreases. C) Increases. D) The fringes disappear. Show Answer Correct Answer: C) Increases. 58. Mark the correct options: A) If the incident rays are converging, we have a real object. B) If the final rays are converging, we have a real image. C) The image of a virtual object is called a virtual image. D) If the image is virtual, the corresponding object is called a virtual object. Show Answer Correct Answer: B) If the final rays are converging, we have a real image. 59. According to Huygens' principle, each point on a wavefront acts as: A) A point source of new plane waves. B) A reflector of incoming rays. C) A source of secondary spherical wavelets. D) A center for destructive interference only. Show Answer Correct Answer: C) A source of secondary spherical wavelets. 60. A point source of light creates ..... wavefront A) Spherical. B) Cylindrical. C) Plane. D) Parabolic. Show Answer Correct Answer: A) Spherical. 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