Wave Optics Mock Test – Class 12 Physics

1. Two spherical wavefronts from the same point source are observed at times and , where . If the wave speed is , the increase in radius is

2. A graph description is given below.

The source pair more suitable for sustained interference is

3. The distance between the first and fifth bright fringes on the same side in a Young's double-slit experiment is . The fringe width is

4. Polarised sunglasses reduce glare because they make use of the fact that light waves can have their vibrations

5. A graph description is given below.

The graph should show that

6. When a thin sheet is placed in front of the upper slit in a symmetric Young's double-slit setup, the central bright fringe shifts

7. In a wave equation, the phase at a point may contain terms such as and . For these terms to be compared or subtracted, both must have the unit

8. Consider the following statements about reflection of a plane wavefront at a plane surface.
Statement I: The incident ray, reflected ray, and normal lie in the same plane.
Statement II: The angle of incidence is equal to the angle of reflection.
Statement III: The reflected wavefront is drawn as the backward envelope only.

9. Use the intensity pattern described below.

The width represents

10. Total internal reflection can occur only when light tries to travel

11. Huygens' principle states that every point on a given wavefront

12. Use the observation below.

The best explanation is that the glare is

13. Colours seen in a thin soap film in reflected light are mainly due to

14. The reflected light from a dielectric surface is strongest in polarisation when the incidence angle is

15. Use the arrangement described below.

The corresponding rays should be drawn

16. Two coherent beams have intensities and . At a point, their phase difference is . The resultant intensity at that point is

17. In a Young's double-slit experiment, light of wavelength is used. A transparent sheet of refractive index and thickness is introduced in front of one slit. The fringe pattern shifts by

18. A learner compares interference, diffraction, and polarisation in a wave-optics summary.
Statement I: Interference depends on superposition and phase difference.
Statement II: Diffraction depends on spreading due to finite apertures or obstacles.
Statement III: Polarisation depends on the transverse vibration direction of light.

19. A double-slit experiment has , , and . The second dark fringe from the central bright fringe is located at

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

21. A claim says, “In single-slit diffraction, a wider central maximum means a wider physical slit.” The better evaluation is that

22. If two coherent waves have intensity ratio , the ratio of their amplitudes is

23. A source used for a clear double-slit pattern is changed from monochromatic light to a broad mixture of wavelengths. The pattern becomes less sharply defined away from the centre mainly because

24. Two coherent beams have intensities in the ratio . The ratio is

25. Which observation most directly points to the need for superposition of light waves?

26. Constructive interference occurs at a point when the path difference between two coherent waves is

27. A transparent medium has Brewster angle . Light of wavelength in air enters the medium. The wavelength inside the medium is

28. Plane-polarised light of intensity first passes through an analyser at to its vibration direction and then through a second analyser at to the original vibration direction. The final intensity is

29. Two coherent light waves have perpendicular states of polarisation when they overlap. The interference contrast is poor because

30. For reflection at a plane surface in the same medium, if is the angle of incidence and is the angle of reflection, Huygens' construction gives

31. A comparison table for wavefronts is shown below.

The row that should be revised is

32. In an interference setup, very wide sources are usually avoided because they tend to

33. A table shows parameter changes in Young's double-slit experiment.

The row that should be revised is

34. Two equal-amplitude light waves arrive at a point exactly out of phase. The resultant disturbance is zero at that point because

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

36. A point in a double-slit experiment receives two waves of equal intensity . The path difference is first and then is increased by . The change in resultant intensity is

37. A record of three wavefronts is shown below.

The row that needs correction is

38. Light is incident from air into glass. If , , and , the value of is

39. For a single slit of width , the approximate angular width of the central maximum is

40. A microscope objective has numerical aperture . The resolving power is improved by

41. A table describes rays incident from a denser medium into a rarer medium.

The row that does not fit total internal reflection is

42. 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

43. In single-slit diffraction, the first minimum occurs when the path difference between waves from the top and bottom edges of the slit is

44. A single slit is illuminated by light of wavelength . If the entire setup is immersed in a liquid where the wavelength becomes , while slit width remains unchanged, the angular width of the central maximum becomes

45. Two crossed ideal polarisers transmit no light. When a third ideal polariser is inserted between them with its axis neither parallel nor perpendicular to the first, some light may pass because

46. For a microscope, the numerical aperture changes from to , and the wavelength changes from to . The ratio of the new limiting resolution distance to the old one is

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

48. In the crossed-polariser arrangement with a middle polariser, maximum final transmission occurs when the middle polariser is placed at

49. Destructive interference for two coherent waves of equal amplitude occurs when the path difference is

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