Wave Optics Mock Test – Class 12 Physics

1. 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

2. A comparison of ray optics and wave optics is shown below.

The case that needs correction is

3. After a plane wavefront fully enters a homogeneous region where the wave speed is lower than before, its shape is expected to

4. A telescope objective has diameter . It observes light of wavelength . The approximate minimum angular separation for resolution is

5. 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.

6. In thin-film interference, the relevant path difference depends more directly on

7. A monochromatic wave travels in a medium with speed and frequency . Its wavelength in that medium is

8. Two coherent light waves have displacements and at the same point and same instant. If the displacements are along the same direction, the resultant displacement is

9. The angular width of the central maximum in single-slit diffraction is doubled when

10. A single slit of width is illuminated by light of wavelength . A screen is placed from the slit. Using the small-angle approximation, the linear width of the central diffraction maximum is

11. At normal incidence on a plane boundary, a light wave enters a medium where its speed changes. The direction of the ray does not bend because

12. Use the passage below to answer the question.

The observation supports the idea that

13. In ray optics, the word “ray” mainly represents the

14. A data sheet gives the following pairs for a monochromatic light wave in one medium.

The row that does not fit the usual meaning of the quantity is

15. Consider the following statements about refraction of light at a plane boundary.
Statement I: Frequency remains unchanged when light enters another medium.
Statement II: Wavelength changes when the wave speed changes.
Statement III: A larger refractive index means a larger speed of light in the medium.

16. For light incident from air on a transparent medium, the graph of against refractive index should be

17. A student says, “Sound waves in air should be polarised in the same way as light.” The best correction is that

18. A table connects path difference with phase difference for light of wavelength .

The row that should be revised is

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

20. A student draws only straight rays through a slit and predicts a perfectly sharp light patch on the screen. This prediction is most likely to be poor when

21. A polarising sheet is used to test light from two sources.

The best classification is

22. A claim says, “When light enters glass from air, its colour changes because its frequency changes.” The best evaluation of this claim is that

23. A claim says, “For maximum intensity, two interfering beams must have equal individual intensities.” The best response is that

24. A Young's double-slit experiment has , , and . The position of the second bright fringe from the centre is

25. A comparison table for interference and diffraction is shown below.

The row that should be revised is

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

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

28. A notebook table lists some wave-optics symbols and units.

The row that must be revised is

29. A student writes that single-slit minima occur at . This should be corrected because

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

31. The distance between two consecutive plane wavefronts of the same monochromatic light in a medium is . If the frequency is , the speed of light in that medium is

32. Two independent ordinary bulbs do not usually produce a stable interference pattern on a screen because

33. In the usual textbook convention, the plane of vibration of plane-polarised light is the plane containing

34. The first dark fringe in a Young's double-slit experiment is located at from the centre. The third dark fringe on the same side, using the usual dark-fringe counting from the centre, is at

35. A transverse wave travelling along the -axis has vibrations only along the -axis. This wave is

36. Intensity in wave optics is connected more directly with

37. Consider the following statements about polarisation by reflection.
Statement I: At Brewster angle, the reflected light is plane-polarised in the ideal case.
Statement II: Brewster's law for incidence from air can be written as .
Statement III: At Brewster angle, the reflected and refracted rays are parallel.

38. A data table lists bright-fringe positions in a double-slit experiment.

The entry that should be corrected is for order

39. A student draws the electric field vibration of reflected light at Brewster angle along the reflected ray. The drawing is incorrect because

40. A table compares equal and unequal intensity interference.

The row that should be revised is

41. Light travels from medium to medium , with , , and . The value of is

42. The ability of light to be polarised shows that light waves are

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

The row that needs correction is

44. A claim says, “Making a slit narrower should make the light patch narrower because the opening is smaller.” The wave-optics correction is that

45. In a single-slit diffraction pattern, the secondary maxima are much less intense than the central maximum mainly because

46. A graph description is given below.

The source pair more suitable for sustained interference is

47. In Young's double-slit notation, the separation between the two slits is usually denoted by

48. 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

49. A stable interference pattern from two light beams is obtained only when the beams have

50. A pair of crossed polarisers has a middle polariser inserted at angle to the first polariser. For unpolarised incident light of intensity , the final intensity is proportional to