Wave Optics Mock Test – Class 12 Physics

1. Two light waves of the same frequency travel in the same medium. Their amplitudes are in the ratio . If intensity is proportional to the square of amplitude, the ratio of their intensities is

2. Consider the following statements about a polariser and analyser.
Statement I: A polariser can convert unpolarised light into plane-polarised light.
Statement II: An analyser can be used to detect the vibration direction of plane-polarised light.
Statement III: Crossed polariser and analyser axes give maximum transmitted intensity in the ideal case.

3. A row of fringes is observed moving outward from the central bright fringe on one side. The correct order is

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

5. A table compares thin-film observations.

The row that needs correction is

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

7. The fifth bright fringe in a Young's double-slit experiment is observed at from the centre. A transparent sheet introduced before one slit shifts the whole pattern by . The extra optical path introduced by the sheet is

8. Two coherent sources produce maximum and minimum intensities and , respectively. The ratio of the individual intensities of the two sources is

9. A beam of unpolarised light is passed through a polariser and then an analyser. When the analyser is rotated through , the transmitted intensity varies periodically. This observation shows that

10. For light going from medium to medium , where , the critical angle satisfies

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

12. 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.

13. A graph description is given below.

The graph should show that

14. A student compares two diffraction arrangements.

The correct classification is

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

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

17. A graph is described below.

The dark points occur at

18. When unpolarised light is incident on a transparent surface at the polarising angle, the reflected light is

19. 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

20. 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

21. If the slit width in a single-slit diffraction experiment is decreased while the wavelength is kept fixed, the central maximum becomes

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

The row that should be revised is

23. Use the construction record below.

The equality of the wavelet radii occurs because

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

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

26. A table describes telescope resolution.

The row that should be revised is

27. Diffraction is most appreciable when the aperture width is

28. White light is used in a double-slit experiment. The first-order red maximum has . For violet light of wavelength , the mathematical order value needed to appear at the same screen position is

29. A statement says, “When two equal beams interfere constructively, energy is created because the maximum intensity becomes instead of .” The correct interpretation is that

30. Two coherent sources illuminate a screen, but one mirror in the path vibrates irregularly. The observed fringes are likely to blur because the vibration

31. A table lists symbols used in Young's double-slit experiment.

The row that should be corrected is

32. The resolving power of an optical instrument is closely connected with diffraction because

33. A statement about reflection says, “The incident wavefront and reflected wavefront make equal angles with the reflecting surface.” This is consistent with the law because

34. For a double-slit experiment with , , and , the distance of the first dark fringe from the central bright fringe is

35. 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

36. Introducing a thin transparent sheet in front of one slit in Young's double-slit experiment mainly changes

37. Plane-polarised light is passed through two analysers in succession. The first analyser makes with the incident vibration direction, and the second analyser is parallel to the first. If the incident intensity is , the final intensity is

38. For a plane wavefront crossing from medium into medium , with refractive indices and , the wave-speed relation used in refraction is

39. For a ray incident from medium into medium , the incidence angle is and the refracted angle is . If , the relation between and for ordinary refraction is

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

41. Use the reflection arrangement described below.

If the incident part near travels a distance in the same time and in the same medium, the relation between these distances is

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

43. The first bright fringe in a Young's double-slit experiment is at from the centre. The fourth bright fringe on the same side is at

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

45. A claim says, “If two light waves overlap, energy is created at bright regions and destroyed at dark regions.” The better interpretation is that

46. A double-slit pattern has equally spaced bright and dark fringes. If the distance from the central bright fringe to the first dark fringe is , the fringe width is

47. A derivation note for Young's double-slit experiment contains the following steps.

The row that should be corrected is

48. Two overlapping waves at a point have displacements and at the same instant. The resultant displacement is

49. A table gives results for unpolarised light of intensity passing through ideal polarising arrangements.

The row that should be corrected is

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

The row that should be revised is