Wave Optics Mock Test – Class 12 Physics

1. According to the Rayleigh criterion, two point images are just resolved when

2. Use the graph description below.

The angular width of the central maximum is

3. A graph is plotted with on the vertical axis and on the horizontal axis for monochromatic light. If the slope is , the wavelength is

4. Assertion: Two independent ordinary lamps of the same average colour usually do not give sustained interference fringes.
Reason: Same average colour alone does not guarantee a constant phase difference between the emitted waves.

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

6. In light from a distant star, a shift of spectral lines toward longer wavelength is called redshift. It usually indicates that the source and observer are

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

8. 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

9. Use the case below.

The case is suitable for observing sustained interference mainly because it provides

10. 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

11. In the usual small-angle treatment of Young's double-slit experiment, the path difference at screen coordinate is approximately

12. Newton's rings are circular because the air-film thickness between a plano-convex lens and a glass plate

13. The condition for a single slit gives

14. A single slit gives first minima at on a screen. When the slit width is halved and the screen distance is doubled, the distance between the first minima becomes

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

16. A graph is described below.

The expected trend of the graph is

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

18. A line source is very long compared with the region being observed. In a uniform medium, the wavefronts around it are usually treated as

19. Use the construction record below.

The equality of the wavelet radii occurs because

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

21. A table lists intensity results for two coherent waves.

The row that should be corrected is

22. Use the arrangement described below.

The emergent beam is best described as

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

24. A table compares equal and unequal intensity interference.

The row that should be revised is

25. A phase difference of between two monochromatic waves means that the waves are

26. A graph is described below.

The dark points occur at

27. A construction based on Huygens' principle uses several points on an old wavefront. The physically meaningful new wavefront is not obtained by joining the centres of the secondary wavelets because

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

The entry that should be corrected is for order

29. A glass plate has polarising angle such that . At this angle, the refracted angle satisfies

30. A comparison table for wavefronts is shown below.

The row that should be revised is

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

32. Light travels from water into air at an oblique angle. If , the refracted wavefront in air advances in such a way that the refracted ray bends

33. The superposition principle for light waves states that when two waves overlap at a point, the resultant disturbance is

34. 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

35. Consider the following statements about fringe width in Young's double-slit experiment.
Statement I: The spacing between consecutive bright fringes is equal to the spacing between consecutive dark fringes.
Statement II: The distance between a bright fringe and its nearest dark fringe is .
Statement III: Increasing while keeping and fixed increases .

36. A derivation note for refraction includes the following entries.

The entry that should be removed is

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

38. A ray is incident from air on a glass plate. At the polarising angle, the refracted ray makes with the normal. The refractive index of glass is

39. In Young's double-slit experiment with white light, the central fringe is white because

40. 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

41. In an isotropic medium, rays associated with a wavefront are drawn

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

43. A point on the screen in a Young's double-slit experiment is at . This point is

44. Assertion: At the polarising angle, .
Reason: At the polarising angle, the reflected and refracted rays are perpendicular.

45. A transparent medium has refractive index . The polarising angle for light incident from air is

46. A double-slit experiment uses and . For light of wavelength , the screen coordinate where the path difference first becomes is

47. Coherent waves with intensities and can produce a maximum resultant intensity of

48. A telescope working at wavelength has objective diameter . Another telescope working at is to have the same diffraction-limited angular resolution. Its objective diameter should be

49. A student compares two diffraction arrangements.

The correct classification is

50. A table about Newton's rings in reflected light is shown below.

The row that should be revised is