Wave optics: Huygens’ principle, interference and diffraction - Question Bank

1. The intensity ratio of the brightest to the darkest fringe in Young's double-slit experiment, if the intensities of the two sources are I₀ and 9I₀, is:
A) 4:1
B) 9:1
C) 16:1
D) 1:0
2. The intensity of light in an interference pattern varies between:
A) 0 and I_max
B) I_min and I_max
C) 0 and I_min
D) I_max and 2I_max
3. In the Fraunhofer diffraction experiment, the source and screen are:
A) At infinite distances from the aperture
B) At finite distances from the aperture
C) One at finite and the other at infinite distance
D) Not relevant to the pattern
4. In the Fresnel diffraction experiment, the source and screen are:
A) At finite distances from the aperture
B) At infinite distances from the aperture
C) One at finite and the other at infinite distance
D) Not relevant to the pattern
5. The fringe spacing in Young's double-slit experiment is directly proportional to:
A) Distance of screen from slits
B) Distance between slits
C) Wavelength of light
D) Refractive index of medium
6. The angular width of the central maximum in single-slit diffraction is inversely proportional to:
A) Slit width
B) Wavelength
C) Screen distance
D) Intensity
7. The difference between interference and diffraction is that diffraction involves superposition of waves originating from:
A) Different parts of the same wavefront
B) Two coherent sources
C) Two independent sources
D) A single source split into two
8. The difference between interference and diffraction is that interference involves superposition of waves from:
A) Two or more coherent sources
B) A single source
C) Two independent sources
D) Any number of sources
9. If the slit separation 'd' in Young's double-slit experiment is very small compared to the distance 'D' to the screen, then:
A) Interference fringes are clearly visible
B) Diffraction effects dominate
C) No fringes are observed
D) Only a single bright spot is seen
10. In Young's double-slit experiment, if the wavelength of light is increased, the fringe width:
A) Increases
B) Decreases
C) Remains unchanged
D) Becomes zero
11. The resultant amplitude in interference when two waves of amplitudes A₁ and A₂ interfere destructively is:
A) A₁ + A₂
B) A₁ - A₂
C) √(A₁² + A₂²)
D) (A₁ - A₂)/2
12. The resultant amplitude in interference when two waves of amplitudes A₁ and A₂ interfere constructively is:
A) A₁ + A₂
B) A₁ - A₂
C) √(A₁² + A₂²)
D) (A₁ + A₂)/2
13. Huygens' principle states that every point on a wavefront is a source of:
A) Secondary wavelets propagating with the speed of light
B) Secondary wavelets propagating with half the speed of light
C) Secondary wavelets propagating with twice the speed of light
D) Secondary wavelets propagating with zero speed
14. To observe diffraction, the size of the obstacle or aperture should be:
A) Comparable to the wavelength of light
B) Much larger than the wavelength of light
C) Much smaller than the wavelength of light
D) Any size
15. In diffraction from a single slit, the central maximum is twice as wide as the other secondary maxima. This statement is:
A) True
B) False
C) Partially true
D) Depends on the wavelength
16. The intensity at a point in a Young's double-slit experiment where the path difference is Δx is proportional to:
A) cos²(πΔx/λ)
B) sin²(πΔx/λ)
C) cos(πΔx/λ)
D) sin(πΔx/λ)
17. The condition for the nth dark fringe in Young's double-slit experiment is a path difference of:
A) nλ
B) (n+1/2)λ
C) (2n+1)λ/2
D) (2n-1)λ
18. The condition for the nth bright fringe in Young's double-slit experiment is a path difference of:
A) nλ
B) (n+1/2)λ
C) (2n+1)λ/2
D) (2n-1)λ/2
19. If the refractive index of the medium in Young's double-slit experiment is 'μ', the fringe width will:
A) Increase
B) Decrease
C) Remain unchanged
D) Become zero
20. The angular position of the first diffraction minimum for a single slit of width 'a' is given by:
A) sin⁻¹(λ/a)
B) sin⁻¹(a/λ)
C) sin⁻¹(2λ/a)
D) sin⁻¹(a/2λ)
21. When white light is used in Young's double-slit experiment, the fringes on either side of the central white fringe are:
A) Colored
B) White
C) Black
D) Monochromatic
22. If white light is used in Young's double-slit experiment, the central fringe is:
A) White
B) Red
C) Violet
D) Black
23. The fringe width (β) in Young's double-slit experiment is given by:
A) λD/d
B) λd/D
C) Dd/λ
D) λ/(Dd)
24. What is the condition for destructive interference in terms of path difference (Δx)?
A) Δx = nλ
B) Δx = (2n+1)λ/2
C) Δx = (2n+1)λ
D) Δx = nλ/2
25. What is the condition for constructive interference in terms of path difference (Δx)?
A) Δx = (2n+1)λ/2
B) Δx = nλ
C) Δx = (2n+1)λ
D) Δx = nλ/2
26. The phenomenon of interference is observed when light waves from:
A) Two independent sources overlap
B) A single source split into two coherent sources overlap
C) Two independent sources with same frequency overlap
D) Two independent sources with different frequencies overlap
27. In a diffraction pattern, the intensity of secondary maxima:
A) Decreases rapidly with increasing order
B) Increases rapidly with increasing order
C) Remains constant
D) Is zero
28. The condition for the nth secondary maximum in single-slit diffraction is approximately:
A) a sin θ = (n+1/2)λ
B) a sin θ = nλ
C) a sin θ = (2n+1)λ/2
D) a sin θ = (2n-1)λ/2
29. The condition for the nth minimum in single-slit diffraction is given by:
A) a sin θ = nλ
B) a sin θ = (n+1/2)λ
C) a sin θ = (2n+1)λ/2
D) a sin θ = (2n-1)λ/2
30. If the slit width in a single-slit diffraction experiment is decreased, the width of the central maximum:
A) Increases
B) Decreases
C) Remains unchanged
D) Becomes zero
31. In single-slit diffraction, the angular width of the central maximum is given by:
A) 2λ/a
B) λ/a
C) a/λ
D) 2a/λ
32. In single-slit diffraction, the first minimum is observed when the path difference between the diffracted rays from the edges of the slit is:
A) λ
B) λ/2
C) 2λ
D) 0
33. Diffraction is more pronounced when the size of the obstacle is:
A) Much larger than the wavelength of light
B) Comparable to the wavelength of light
C) Much smaller than the wavelength of light
D) Independent of the wavelength of light
34. Diffraction of light is the phenomenon of:
A) Bending of light around obstacles
B) Splitting of light into its constituent colors
C) The superposition of waves
D) The propagation of light in straight lines
35. Coherent sources of light are sources that emit waves with:
A) Same frequency and constant phase difference
B) Different frequencies and constant phase difference
C) Same frequency and variable phase difference
D) Different frequencies and variable phase difference
36. In Young's double-slit experiment, the minimum intensity is observed when the path difference is:
A) Zero
B) λ/2
C) λ
D) 3λ/2
37. In Young's double-slit experiment, the maximum intensity is observed when the path difference is:
A) Zero
B) λ/2
C) λ
D) 3λ/2
38. If two coherent sources of light have intensities in the ratio 1:9, then the ratio of amplitudes of the waves is:
A) 1:3
B) 1:9
C) 1:81
D) 3:1
39. The intensity of light in Young's double-slit experiment is proportional to:
A) The square of the amplitude
B) The amplitude
C) The square root of the amplitude
D) The inverse of the amplitude
40. In Young's double-slit experiment, if the distance of the screen from the slits is doubled, the fringe width will be:
A) Halved
B) Doubled
C) Unchanged
D) Four times
41. In Young's double-slit experiment, if the distance between the slits is halved, the fringe width will be:
A) Halved
B) Doubled
C) Unchanged
D) Four times
42. The condition for destructive interference in terms of phase difference (Δφ) is:
A) Δφ = 2nπ
B) Δφ = (2n+1)π
C) Δφ = nλ
D) Δφ = (2n+1)λ
43. The condition for constructive interference in terms of phase difference (Δφ) is:
A) Δφ = (2n+1)π
B) Δφ = 2nπ
C) Δφ = (2n+1)λ/2
D) Δφ = nλ
44. If the phase difference between two light waves is π, then the interference is:
A) Constructive
B) Destructive
C) Neither constructive nor destructive
D) Partially constructive
45. For destructive interference, the path difference between two light waves should be:
A) A multiple of λ
B) An even multiple of λ/2
C) An odd multiple of λ/2
D) Zero
46. The condition for constructive interference of two light waves is that the path difference between them should be:
A) An odd multiple of λ/2
B) An even multiple of λ/2
C) A multiple of λ
D) Zero
47. Which phenomenon supports Huygens' wave theory of light?
A) Reflection
B) Refraction
C) Diffraction
D) All of the above
48. Huygens' principle is used to determine the position of a wavefront at a:
A) Previous instant
B) Future instant
C) Same instant
D) Arbitrary instant
49. According to Huygens' principle, each point on a wavefront acts as a source of:
A) Secondary spherical waves
B) Secondary circular waves
C) Secondary plane waves
D) Secondary elliptical waves
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