1st Year Physics Chapter 9 Physical Optics Notes MCQs Bank

physics 11th notes Chapter 9

1. In Michelson interferometer to switch the fringe from bright to dark the mirror should be displaced through?


2. Which one of the following properties of light does not change with the nature of the medium?


3. The bending of a beam of light when it passes from one medium to another is known as:


4. Two sources of light are coherent if they emit rays of?


5. In double slit experiment, we observe?


6. In an interference pattern:


7. Optically active crystals rotate the?


8. The wavelength of X – rays is of the order of?


9. In Young’s double slit experiment, the distance between two adjacent bright fringes, ∆𝑦 is:


10. A compact disc having rulings of 0.5 μm each wide shows colors under white light due to?


11. When crest of one wave falls over the trough of the other wave, this phenomenon is known as


12. The center of Newton’s rings is_________ due to destructive interference:


13. Bending of light around the edges of an obstacle is known as:


14. The distance between two consecutive wave fronts is called:


15. When the Newton’s rings are observed with reflected light, the central spot is:


16. When the Newton’s rings are observed with transmitted light, the central spot is:


17. Sodium chloride in a flame gives out pure:


18. The effective path difference between two reflected beams, in x-ray diffraction by crystal is:


19. The velocity of light was determined accurately by?


20. The condition for constructive interference of two coherent beams is that the path difference should be


21. Light on passing through a Polaroid is?


22. Longitudinal waves do not exhibit?


23. A polarizer is used to?


24. In Young double slit experiment, if white light is used


25. In a double-slit experiment, if one of the two-slit is covered then?


26. In Young’s double-slit experiment, the separation between the slit is halved and the distance between the slit and screen is doubled. The fringe width is:


27. The photoelectric effect was explained by?


28. In a plane-polarized light electric vibration are:


29. According to Einstein, light travels from one place to another in the form of?


30. In the shadow of a ball the central portion appears bright that happens due to?


31. Which experiment shows that wavelength of light is smaller than that of sound?


32. Diffraction effect is:


33. In the Young double-slit experiment, if white light is used?


34. In Young’s double slit experiment, the fringe spacing is equal to (d=slit separation and D = distance of the screen from slits):


35. The condition of constructive interference of two coherent beams is that the path difference should be?


36. One angstrom is equal to:


37. When the crest of one wave falls over the trough of the other wave, this phenomenon is known as?


38. Signal from the T.V remote control travels:


39. Crystals of material can behave as?


40. A light ray traveling form denser to rarer medium suffers a phase change of:


41. The wavelength of X-rays falling at a glancing angle of 30° on a crystal with atomic spacing 2 x 10⁻¹⁰m for the first-order diffraction is?


42. When light incident normally on thin film, the path difference depends upon?


43. Which one of the following is nearly monochromatic light?


44. A light ray traveling form rarer to denser medium suffers a phase change of:


45. A point source of light placed in a homogenous medium gives rise to?


46. The equation of Michelson’s interferometer is:


47. The appearance of Color in thin films is due to


48. A light ray traveling from denser to rarer medium suffers a phase change of?


49. Huygen wave theory explain?


50. A diffraction grating has 500 lines per mm. Its slit spacing or grating element will be equal to?


51. Soap film exhibit brilliant colors in sun light due to:


52. The blue color of the sky is due to?


53. ________ gives the definition of a metre in terms of the wavelength of red cadmium light.


54. Which one of the following cannot be polarized?


55. The condition for destructive interference of two coherent beams is that the path difference should be


56. 𝑑 sin 𝜃 = 𝑚𝜆 is called:


57. Which is not an optically active substance?


58. In monochromatic red light, a blue book will probably appear to be?


59. When one mirror of a Michelson Interferometer is moved a distance of 0.5 mm, we observe 2000 fringes. What will be a wavelength of light used?


60. The locus of all points in a medium having the same phase of vibration is called?


61. 2𝑑 sin𝜃 = 𝑚𝜆 is called:


Short Questions

1. An oil film spreading over a wet foot path shows colors. Explain how it happens?
2. Can visible (white) light produce interference fringes? Explain.
3. Can you obtain Newton’s rings with transmitted light? If yes be different from that obtained with reflected light?
4. Define diffraction of light?
5. Define optical rotation. Give its practical use.
6. Define phenomenon of interference of light waves?
7. Define polarization of light.
8. Define the term, wave front?
9. Define wave front and spherical wave front.
10. Define wave fronts, also give its types.
11. Describe four uses of Michelson’s interference?
12. Describe the uses of a Polaroid as an analyzer and as a polarizer?
13. Describe two uses of diffraction grating?
14. Describes the factors upon which the fringe spacing (or width) in Young double slit experiments can be increased?
15. Explain whether a path difference of λ/4 is associated with a constructive interference or destructive or neither of them?
16. Explain whether Young’s experiment is an experiment for studying interference or diffraction effects of light?
17. Explain why two distant flash lights will not produce an interference pattern?
18. Explain with diagram “the second part of Huygens’s principle?
19. How can the distance between interference fringes affect appear between the slits of Young’s experiment,
20. How is Newton’s rings formed?
21. How the distance between interference fringes affected by the separation between the slits of Young‘s experiment? Can fringes disappear?
22. How would you distinguish between un-polarized and plane polarized lights? 
23. How would you manage to get more orders of spectra using a diffraction grating?
24. If white light is used to illuminate the diffraction grating what kind of diffraction pattern is produced?
25. In Michelson interference, why a fringe is shifted when a mirror is moved through λ/2?
26. In the white light spectrum obtained with diffraction grating, the third order image of a wavelength coincides with the forth order image of a second wavelength. Calculate the ratio of the two wavelengths?
27. In the Young’s experiment, one of the slits is covered with blue filter and other with red filter. What would be the pattern of light intensity on the screen?
28. In young’s double slit experiment, the wavelength of the light is doubled, what will happen to the spacing (or width) of fringes?
29. State Huygens’s principle?
30. The center of Newton’s ring is dark. Why?
31. Under what conditions can interference of light take place?
32. Under what conditions two or more sources of light behave as coherent sources?
33. What are conditions for detectable interference of light?
34. What are dependence factors of fringe spacing in Young’s double slit experiment?
35. What are different methods for obtaining the polarized light?
36. What are different substances for obtaining polarized light by selective absorption?
37. What are Newton’s formed?
38. What are the main facts which support the following statements: (a). The light is propagated in the form of waves and not a corpuscular. (b). Light travels in the form of transverse waves. (c). Light waves are much shorter than sound waves.
39. What aspect of the nature of light is proved by the phenomenon of polarization?
40. What condition must be met by interfering beams to observe interference?
41. What conditions two or more sources of light behave as coherent sources?
42. What do you mean by grating elements of a diffraction grating?
43. what do you understand by thin film?
44. What is constructive interference?
45. What is difference between interference and diffraction fringes?
46. What is diffraction grating?
47. What is diffraction grating?
48. What is diffraction of light?
49. What is distance between two adjacent dark fringes?
50. What is Michelson interference?
51. What is plane polarized light. Give some applications of polarized light?
52. What is polarization of light?
53. What is the condition for diffraction?
54. What is the difference between interference and diffraction?
55. What is the necessary conditions for the path difference between two waves that interfere. (a) Constructively (b) Destructively
56. What will happen when light is made incident on the thin film of irregular thickness at different angles?
57. Which of the following can occur in a) Longitudinal b) and transverse waves.Refraction,interference, diffraction dispersion and polarization?
58. Why is center of Newton’s rings dark?
59. Why it is impossible to have diffraction of x – rays by laboratory diffraction grating?
60. Why the Polaroid sun glasses are better than ordinary sun glasses?
61. Write any two processes to obtain plane polarized light?
62. Write three factors on which interference in thin film depends?
63. Write two steps of Huygens’s principle.

Long Questions

1. What are conditions for constructive and destructive interference?
2. What is the diffraction of light?
3. Under what conditions two or more sources of light behave as coherent sources?
4. The centre of Newton‟s rings are dark. Why?
5. Write down two methods to obtain plane polarized beam of light.
6. State Huygen‟s principle.
7. Write the conditions to observe the phenomenon of interference of light.
8. In a double slit experiment the second order maximum occurs at length is  = 0.025o . The wave 650 nm. Find the slit separation.
9. Define optical rotation. Give its practical use.
10. Define diffraction grating and grating element.
11. Explain Briefly Young‟s double slit experiment.
12. Describe the construction and working of Michelson‟s Interferometer.
13. Define Diffraction of light. Discuss the diffraction of light through a narrow slit.
14. What is Diffraction grating and obtain the grating equation to find the wave length of light?
15. Explain diffraction of x-rays through crystals. Derive Braggs equation.
16. Explain diffraction of x-rays through crystals. Derive Bragg‟s equation to study crystal structure.
17. Light of wavelength 546nm is allowed to illuminate the slits of Young’s experiment. The separation between the slits is 0.10 mm and the distance of the screen form the slits where interference effects are observed is 20 cm. At what angle the first minimum will fall? What will be the linear distance on the screen between adjacent maxima?
18. Calculate the wavelength of light illuminates two, slits 0.5mm apart and produces an interference pattern on a screen placed 200 cm away from the slits. The first bright fringe is observed at distance of 2.4 mm from the central bright image.
19. In a double slit experiment the second order maximum occurs at an angle of 0.25 degree. The wavelength is 650 nm. Determine the slit separation.
20. A monochromatic light of wavelength 588nm is allowed to fall on the half silvered plate G1, in the Michelson interferometer. If mirror M1 is moved through 0.233mm, how many fringes will be observed to shift?
21. A second order spectrum is formed at an angle of 38 degree when light falls normally on a diffraction grating having 5400 lines per centimeter.Determine wavelength of the light used.
22. A light is incident normally on a grating, which has 2500 lines per centimeter. Compute the wavelength of a spectral line for which the deviation in second order is 15 degree.
23. Sodium light of wavelength 589 nm is incident normally on a grating having 3000 lines per centimeter. What is the highest order of the spectrum obtained with this grating?
24. Blue light of wavelength 480 nm illuminates a diffraction grating. The second order image is formed at an angle of 30 degree from the central image. How many lines in a centimeter of the grating have been ruled?
25. X-rays of wavelength 0.15nm are observed to undergo a first order reflection at a Bragg angle of 13.3 degree from a quartz (SiO2) crystal. What is the interplanar spacing of the reflecting planes in the crystal?
26. X-ray beam of wavelength undergoes a first order reflection from a crystal when its angle of incident to a crystal face is 26.5 degree, and an X-ray beam of wavelength 0.097nm undergoes a third order reflection when its angle of incidence to that face is 60 degree. Assuming that the two beams reflect from the same family of planes, calculate (a) the interplanar spacing of the planes and (b) wavelength.

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