Wave Optics Mock Test – Class 12 Physics

1. Two coherent beams have amplitudes and . Another pair has amplitudes and . Assuming the same phase stability, the first pair gives better dark-bright contrast mainly because

2. When a plane wavefront enters a second medium obliquely, refraction occurs because

3. Two monochromatic waves reach a point with phase difference . The closest phase classification is

4. A partially polarised beam is passed through a rotating analyser. The intensity changes between and , where . This indicates that

5. A microscope is used first with air and then with an oil-immersion medium of higher refractive index, keeping the objective geometry suitable. The resolution improves mainly because

6. A polariser is an optical device that

7. Given and for two coherent waves, the fringe visibility is

8. A table lists dark-fringe positions for a Young's double-slit pattern.

The entry that needs correction is for the

9. For a telescope with a circular objective of diameter , the minimum angular separation that can be resolved is approximately

10. In a double-slit experiment, light of wavelength gives fringe width . The slit separation is reduced by , and the wavelength is changed to , with unchanged. The new fringe width is

11. In Young-type interference, the two narrow slits are usually illuminated by the same source before acting as secondary sources. The main reason is to

12. In a single-slit diffraction pattern, the second minimum occurs at a direction where

13. Intensity in wave optics is connected more directly with

14. During Huygens' construction for a plane wavefront in a homogeneous medium, the new position after a short time remains plane mainly because

15. For a Brewster-angle setup with , the polarising angle is closest to

16. Match the observation with the wave-optics idea most closely involved.

17. An analyser is used after a polariser mainly to

18. A light beam of unpolarised intensity passes through an ideal polariser and then an analyser at to the polariser axis. The transmitted intensity after the analyser is

19. A graph is described below.

The repetition occurs because

20. Combining Snell's law with the Brewster condition gives Brewster's law. The correct derivation route is

21. Inside glass, a ray approaches a glass-air boundary. As the angle of incidence in glass is gradually increased, the angle of refraction in air

22. A wavefront is best described as a surface joining points of a light wave that have

23. A claim says, “At Brewster angle, the refracted ray is completely absent.” The best correction is that

24. Which pair of wave quantities has the same basic unit type?

25. A graph is plotted for a transparent medium using . The vertical axis is , and the horizontal axis is . The slope of the graph is

26. The first dark fringe on one side of the central bright fringe corresponds to

27. If the intensity ratio of two coherent sources becomes more unequal, the visibility of fringes generally

28. Unpolarised light of intensity passes through three ideal polarisers. The second polariser is at to the first, and the third is at to the second. The final intensity is

29. A point on the screen in Young's double-slit experiment is measured by its distance from the central line. The central line is the line

30. A small circular opening and a large circular opening are used with the same light. If denotes the opening diameter, the statement that best expresses the ray-to-wave transition is

31. A comparison for two equal-intensity coherent waves is shown below.

The row that needs correction is

32. Which statement describes two points separated by one wavelength along the direction of propagation of a monochromatic light wave?

33. A point on a screen receives light from two coherent sources. If one source is shifted so that its phase at the point changes by a constant amount everywhere in time, the interference pattern is expected to

34. Waves with amplitudes and interfere coherently. The ratio of maximum to minimum intensity is

35. Malus' law gives the intensity transmitted by an analyser when plane-polarised light of intensity is incident on it. The relation is

36. In Huygens' construction for a spherical wavefront, the secondary wavelets emitted from points on the old spherical wavefront have equal radii after the same time interval when the medium is homogeneous. The new wavefront is then

37. A small portion of sunlight reaching a laboratory window is often treated as a plane wavefront because

38. A graph of single-slit diffraction intensity is compared with a double-slit interference pattern. A key difference is that the single-slit central maximum is

39. A table compares possible source pairs for observing sustained interference.

The row that needs correction is

40. A telescope objective diameter is doubled while the wavelength of light remains the same. The minimum resolvable angular separation becomes

41. Consider the following statements for two coherent waves of equal amplitude.
Statement I: gives constructive interference.
Statement II: gives destructive interference.
Statement III: gives constructive interference.

42. A set of parallel plane wavefronts in a uniform medium has equal spacing. This equal spacing physically represents

43. Plane wavefront moves through a homogeneous medium with speed . After a time , each secondary wavelet has radius

44. A claim says, “If two polarisers are crossed, inserting another polariser between them can never increase transmission.” The best evaluation is that the claim is

45. A table gives measured polarising angles for different transparent media.

The row that should be revised is

46. A graph of transmitted intensity against analyser angle for plane-polarised incident light has maxima at and , and minima at and . This pattern follows from

47. A Young's double-slit setup has fringe width in air. The entire space between the slits and screen is filled with a liquid of refractive index , while and remain unchanged. The new fringe width is

48. Inside a liquid of refractive index , light is incident on the liquid-air surface. Taking air as , the ray is totally internally reflected when

49. A table lists observations related to Brewster's law.

The statement that should be removed is

50. A claim says, “A polariser blocks all light except the part travelling in one direction.” The correct idea is that a polariser selects