Description: Practice Class 12 Physics Chapter 18 Diffraction and Interference MCQs according to the FBISE HSSC-II assessment framework. These questions cover coherent sources, constructive and destructive interference, Young’s double-slit experiment, fringe width, single-slit diffraction and diffraction gratings.
1. Diffraction is the spreading of waves when they pass through an aperture or around an obstacle.
2. Diffraction is most significant when the aperture width is:
3. Interference occurs when two or more waves:
4. For a sustained interference pattern, the sources should be:
5. Coherent sources have a constant:
6. In Young’s double-slit experiment, a bright fringe results from:
7. A dark fringe in Young’s experiment results from:
8. The condition for constructive interference is a path difference of:
9. The condition for destructive interference is a path difference of:
10. The central bright fringe in Young’s experiment has path difference:
11. A path difference of one wavelength corresponds to a phase difference of:
12. A path difference of half a wavelength corresponds to a phase difference of:
13. If two identical waves arrive in phase, their amplitudes:
14. If two identical waves arrive exactly out of phase, their resultant amplitude is:
15. The intensity of a wave is proportional to the:
16. For two equal coherent waves, constructive interference produces an intensity that is:
17. For two equal coherent waves, complete destructive interference produces:
18. In Young’s double-slit experiment, the fringe width is given by:
19. In Young’s experiment, increasing wavelength while keeping other quantities fixed makes fringe width:
20. In Young’s experiment, increasing slit separation makes fringe width:
21. In Young’s experiment, increasing the distance between the slits and screen makes fringe width:
22. The SI unit of fringe width is:
23. Monochromatic light has:
24. When the path difference is 3λ/2, the interference is:
25. When the path difference is 2λ, the interference is:
26. White light in Young’s experiment produces a central fringe that is approximately:
27. Coloured fringes away from the centre with white light occur because different wavelengths have different:
28. Diffraction demonstrates the:
29. A single narrow slit produces a diffraction pattern containing:
30. For single-slit diffraction, the first minimum approximately satisfies:
31. In the single-slit relation a sinθ = λ, a represents the:
32. If slit width is decreased, the diffraction pattern spreads:
33. If wavelength is increased for a fixed slit width, diffraction spreading:
34. A diffraction grating contains a large number of:
35. The principal maxima of a diffraction grating are due to:
36. For normal incidence, the grating equation is:
37. In the grating equation, d is the:
38. For a fixed grating and order, increasing wavelength causes diffraction angle to:
39. For a fixed wavelength, increasing the order of a grating maximum generally increases:
40. The zeroth-order maximum of a diffraction grating occurs at:
41. A grating with more lines per unit length has:
42. A diffraction grating separates light into different wavelengths because different wavelengths diffract through:
43. The resolving power of a diffraction grating improves when the number of illuminated lines:
44. Young’s double-slit experiment is evidence for the:
45. In an interference pattern, adjacent bright fringes are separated by:
46. The phase difference between two waves is related to path difference Δx by:
47. If the screen distance in Young’s experiment is doubled, fringe width becomes:
48. If slit separation in Young’s experiment is doubled, fringe width becomes:
49. The central maximum in single-slit diffraction is approximately:
50. Interference fringes arise from superposition, while diffraction can be viewed as interference between wavelets from:
Chapter-wise Navigation
- Chapter 15: Gravitational Potential
- Chapter 16: Statistical Mechanics and Thermodynamics
- Chapter 17: Simple Harmonic Motion
- Chapter 18: Diffraction and Interference
- Chapter 19: Electrostatics
- Chapter 20: Alternating Current
- Chapter 21: Quantum Physics
- Chapter 22: Nuclear Physics
- Chapter 23: Cosmology
- Chapter 24: Earth Climate
- Chapter 25: Medical Imaging
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Syllabus & SLO Alignment
FBISE syllabus: National Curriculum of Pakistan 2022–23, FBISE Assessment Framework for Physics Grade XII.
Content area: Domain D – Waves
Relevant SLOs: P-12-D-20 to P-12-D-25
Alignment: Diffraction and interference; coherent sources; Young’s double-slit experiment; fringe width; diffraction grating; electron-diffraction interpretations.
Assessment note: The FBISE framework distinguishes summative SLOs used in the final examination from formative SLOs used in teaching-learning. MCQs on this page should be treated as practice aligned to the listed content/SLOs, not as a reproduction of the official FBISE paper.