MCQ Optical Fiber mock test PDF

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MOCK TEST-OPTICAL FIBERS

1. Which law gives the relationship between refractive index of the dielectric? a) Law of reflection b) Law of refraction (Snell’s Law) c) Millman’s Law d) Huygen’s Law

2. Light incident on fibers of angles________the acceptance angle do not propagate into the fiber. a) Less than b) Greater than c) Equal to d) Less than and equal to

3.The ratio of speed of light in air to the speed of light in another medium is called as _________ a) Speed factor b) Dielectric constant c) Reflection index d) Refraction index

4.When λ is the optical wavelength in vacuum, k is given by k=2Π/λ. What does k stand for in the above equation? a) Phase propagation constant b) Dielectric constant c) Boltzmann’s constant d) Free-space constant

5.Optical fibers suffer radiation losses at bends or curves on their paths. a) True b) False

6.The lower energy level contains more atoms than upper level under the conditions of ________________ a) Isothermal packaging b) Population inversion c) Thermal equilibrium d) Pumping

7.The depletion region must be ____________ to allow a large fraction of the incident light to be absorbed in the device(photodiode). a) Thick b) Thin c) Long d) Inactive

8. A perfect semiconductor crystal containing no impurities or lattice defects is called as __________ a) Intrinsic semiconductor b) Extrinsic semiconductor c) Excitation d) Valence electron

9. When a ray of light enters one medium from another medium, which quality will not change? a) Direction b) Frequency c) Speed d) Wavelength

10. Which of the following statements best explain the concept of material absorption? a) A loss mechanism related to the material composition and fabrication of fiber b) A transmission loss for optical fibers c) Results in attenuation of transmitted light d) Causes of transfer of optical power

11. Multimode step index fiber has a large core diameter of range is ___________ a) 100 to 300 μm b) 100 to 300 nm c) 200 to 500 μm d) 200 to 500 nm

12. The performance characteristics of multimode graded index fibers are ___________ a) Better than multimode step index fibers b) Same as multimode step index fibers c) Lesser than multimode step index fibers d) Negligible

13. In single mode fibers, which is the most beneficial index profile? a) Step index b) Graded index

c) Step and graded index d) Coaxial cable

14. Multimode graded index fibers use incoherent source only. a) True b) False

15. Numerical aperture is constant in case of step index fiber. a) True b) False

16. Which among the following misalignments give/gives rise to the occurrence of splice loss? a. Longitudinal separation between the end-faces of fiber b. Angular tilt between fiber ends c. Transverse offset between fiber ends d. All of the above

17. In an optical network, increase in the number of lasers ________the bit rate. a. Increases b. Stabilizes c. Decreases d. None of the above

18.Halide glass fibers have elements from following group of periodic table a.6 b.7 c.8 d.5

19.A ray of light will undergo total internal reflection if it a.Goes from rarer medium to denser medium b. Incident at an angle less than the critical angle

c .Strikes the interface normally d. Incident at an angle greater than the critical angle

20: Which of the following is not due to total internal reflection of light? a.Brilliance of diamond b. Mirage formation c. Optical fibre working d. Rainbow formation

21: The fibres not used nowadays for optical fibre communication system are a. Single-mode fibre b. Multimode fibre c. Coaxial cable 22: In single-mode fibres, the cladding diameter must be at least a.Five times the core diameter b. Thrice the core diameter c. Ten times the core diameter d. Twice the core diameter

23……………. method uses deposition of soot on cylindrical glass rod. a. PCVD b. VAD c. OVPO d. NONE

24. The band of light wavelengths that are too long to be seen by the human eye a. Infrared b. Amber c. Visible d. Ultraviolet

25. After Total Internal Reflection the Meridional ray __________ a) Makes an angle equal to acceptance angle with the axial ray

b) Makes an angle equal to critical angle with the axial ray c) Travels parallel equal to critical angle with the axial ray d) Makes an angle equal to critical angle with the axial ray 26. Consider a single mode fiber having core refractive index n1= 1.5. The fiber length is 12m. Find the time taken by the axial ray to travel along the fiber. a.00μsec b.0.06μsec c. 0.90μsec

27. The dominating effect of thermal noise over the shot noise in photodiodes without internal gain can be observed in wideband systems operating in the range of ________ a.0.4 TO 0.5 micro meter b. 0.8 TO 0.9 micro meter c. 0.3 TO 0.5 micro meter d 0.6 TO 0.7 micro meter

28. The internal gain mechanism in an APD is directly related to SNR. State whether the given is true or false a.true b.false

29. APDs do not operate at signal wavelengths between 1.3 and 1.6μm. a)True b) False

30.-----------relates to slow growth of pre existing flaws in fibre under humid conditions. a.strength b.dynamic fatigue c.static fatigue

31. The ________ ray passes through the axis of the fiber core. a. Reflected b. Refracted c. Meridional d. Skew

32. What is the numerical aperture of the fiber if the angle of acceptance is 16 degree? a. 0.50 b. 0.36 c. 0.20 d. 0.27

33. Absorption losses due to atomic defects mainly include ___________ a. Radiation b. Missing molecules, oxygen defects in glass c. Impurities in fiber material d. Interaction with other components of core

34. The effects of intrinsic absorption can be minimized by ___________ a. Ionization b. Radiation c. Suitable choice of core and cladding components d. Melting

35. How the potential macro bending losses can be reduced in case of multimode fiber? a. By designing fibers with large relative refractive index differences b. By maintaining direction of propagation c. By reducing the bend d. By operating at larger wavelengths

36. A device which converts electrical energy in the form of a current into optical energy is called as ___________ a. Optical source b. Optical coupler c. Optical isolator d. Circulator

37. The frequency of the absorbed or emitted radiation is related to difference in energy E between the higher energy state E2 and the lower energy state E1. State what h stands for in the given equation? E = E2 - E1 = hf a. gravitation constant b. planks constant c. none 38. Multimode step index fiber has ___________ a. Large core diameter & large numerical aperture b. Large core diameter and small numerical aperture

c. Small core diameter and large numerical aperture d. Small core diameter & small numerical aperture

39. Which process gives the laser its special properties as an optical source? a. Dispersion b. Stimulated absorption c. Spontaneous emission d. Stimulated emission

40. In single mode fibers, which is the most beneficial index profile? a. Step index b. Graded index c. Step and graded index d. Coaxial cable

41. P-n photodiode is forward biased. a. True b. False

42. Rayleigh scattering and Mie scattering are the types of _____________ a. Linear scattering losses b. Non-linear scattering losses c. Fiber bends losses d. Splicing losses

43. Stimulated Brillouin scattering is mainly a ___________ a. Forward process b. Backward process c. Upward process d. Downward process

44. The process of excitation of an electron from valence band to conduction band leaves an empty hole in the valence band and is called as ____________ a) Detection b) Absorption c) Degeneration of an electron-hole pair d) Regeneration of an electron-hole pair

45. __________________ always leads to the generation of a hole and an electron. a) Repulsion b) Dispersion

c) Absorption d) Attenuation

46. How is Yam used in optical fibre construction a. as strength member b. as outer cover c. as conductor d. none

47. What is the unit of measurement of the optical attenuation per unit length? a) dB-km b) dB/km c) km/dB d) V

48. Determine the attenuation per kilometer for a fiber whose length is 2 km, output voltage is 2.1 V at a wavelength of 0.85μm. The output voltage increases to 10.7 V when the fiber is cut-back to leave 2 metres. Determine the attenuation per km for the fiber at wavelength 0.85μm. a) 2.8dB/km b) 3.1dB/km c) 3.5dB/km d) 8dB/km

49. ___________ removes the light propagating in the cladding. a) Cladding mode strippers b) Core strippers c) Mode enhancers d) Attenuators

50. The Responsivity of photodiode is 0.294 AW-1at wavelength of 0.90 μm. Determine quantum efficiency. a) 0.405 b) 0.914 c) 0.654 d) 0.249

51. If a photodiode requires incident optical power of 0.70 A/W. Determine photocurrent. a) 1.482 b) 2.457

c) 4.124 d) 3.199

52. In photo detectors, energy of incident photons must be ________________ band gap energy. a) Lesser than b) Greater than c) Same as d) Negligible

53. The fraction of incident photons generated by photodiode of electrons generated collected at detector is known as ___________________ a) Quantum efficiency b) Absorption coefficient c) Responsivity d) Anger recombination

54. The first generation systems of optical fiber communication have wavelengths between ___________ a) 0.2 and 0.3 μm b) 0.4 and 0.6 μm c) 0.8 and 0.9 μm d) 0.1 and 0.2 μm

55. The quantum efficiency of an optical detector should be high. a) True b) False

56. Silicon has indirect band gap energy of __________________ a) 1.2 eV b) 2 eV c) 1.14 eV d) 1.9 eV

57. Silicon has indirect band gap energy of __________________ a) 1.2 eV b) 2 eV c) 1.14 eV d) 1.9 eV

58. ____________ converts the received optical signal into an electrical signal. a) Detector b) Attenuator c) Laser d) LED

59. An optical fiber has core-index of 1.480 and a cladding index of 1.478. What should be the core size for single mode operation at 1310nm? a) 7.31μm b) 8.71μm c) 5.26μm d) 6.50μm

60. An optical fiber has a core radius 2μm and a numerical aperture of 0.1. Will this fiber operate at single mode at 600 nm? a) Yes b) No...